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                                 EXHIBIT 10 (rr)
                       REVOLVING NOTE BETWEEN THE COMPANY
                         AND THE NORTHERN TRUST COMPANY
                               DATED JUNE 30, 1998


 2
                                   Certificate
                        Borrowing Resolution & Incumbency
                                   Corporation

     The undersigned certifies that set forth below is a copy of a Resolution of
the Board of Directors of CDW Computer  Centers,  Inc., an Illinois  corporation
(the  "Corporation",  or the "Borrower")  which Resolution was properly adopted,
has not been modified or rescinded, and is still in effect:

     "Resolved that this  Corporation  borrow from The Northern Trust Company an
amount not to exceed  Twenty-Five  Million and no/100ths  UNITED STATES  DOLLARS
($25,000,000.00  ) at any one  time  outstanding  pursuant  to the  terms of the
Master Note dated as of June 30, 1998 (the foregoing document(s),  together with
any related documents, being collectively referred to as the "Loan Document(s)")
filed with this resolution, the form of which Loan Document(s) is approved; that
the any two of the  "Named"  officers be  designated  to execute and deliver the
Loan  Documents with such changes as (s)he may approve as evidenced by his (her)
execution of the Loan Documents;  that the Secretary or any Assistant  Secretary
be and each hereby is, acting alone,  authorized to, attest the execution;  that
any two of the "Named"  officers of this  Corporation  be  authorized to request
borrowings  under the Loan  Documents,  to execute and deliver from time to time
any notes and other documents and instruments in connection  therewith,  whether
or not  specifically  referenced in the Loan Documents,  and to take any actions
deemed  necessary or  appropriate by such officer to carry out the provisions of
the Loan Documents and such notes and other documents and instruments;  and that
any actions of the type set forth above previously taken by any of the foregoing
officers are hereby approved, adopted and ratified.

     The  undersigned  does hereby further  certify that the persons named below
have been duly elected or  appointed,  have duly  qualified  as, and on this day
are, the "Named"  officers of the  Borrower,  as indicated  below,  and that set
forth opposite the respective  name of each is a sample of the signature of such
person:

       NAME                         OFFICE                    SIGNATURE

Michael P. Krasny                Chairman & CEO          _____________________

Gregory Zeman                      President             _____________________

Harry J. Harczak             Chief Financial Officer     _____________________


Dated as of June 30, 1998.

             Signature _______________________________

             Name:  Michael P. Krasny

             Title:  Chairman, Chief Executive Officer, Secretary and Treasurer

             Name of Borrower:  CDW Computer Centers, Inc.

     The  undersigned  [MAY NOT BE THE  SAME  PERSON  WHO  SIGNS  ABOVE]  hereby
certifies that the person who executed the foregoing portion of this Certificate
on behalf of the Borrower has been duly elected or appointed as Secretary of the
Borrower, and that set forth above is the signature of such person.

               Signature _______________________________

               Type Name:  Harry J. Harczak

               Title:  Chief Financial Officer

               Name of Borrower:  CDW Computer Centers, Inc.


$25,000,000.00                                        Chicago, Illinois
                                                      Note Date:   June 30, 1998

                           LINE OF CREDIT DEMAND NOTE
                    (CORPORATION - FIXED AND FLOATING RATES)
                                  (UNCOMMITTED)

     ON DEMAND,  for value  received,  CDW Computer  Centers,  Inc., an Illinois
corporation (the "Borrower"), promises to pay to the order of THE NORTHERN TRUST
COMPANY,  an Illinois banking  corporation (the "Lender"),  the aggregate unpaid
principal balance of each advance (an "Advance" and collectively the "Advances")
made by the Lender to the  Borrower  hereunder.  The total  principal  amount of
Advances  outstanding  at any one time  hereunder  shall not exceed  TWENTY-FIVE
MILLION AND NO/100ths UNITED STATES DOLLARS ($25,000,000.00).

     The unpaid  principal  balance of each Advance shall bear interest from the
date thereof until its interim maturity date, as reflected in the records of the
Lender or on an annexed schedule (the "Interim Maturity Date") or the occurrence
of a demand for payment hereof,  whichever is earlier,  at the fixed or floating
rate (as the parties may agree) set forth in an annexed schedule or otherwise in
the Lender's  records.  The principal amount of each Advance shall mature and be
payable on its Interim  Maturity Date,  unless the Lender makes prior demand for
payment hereof, as provided below.

     Accrued but unpaid interest on each Advance shall be payable on the earlier
of (a) the last day of each month,  (b) its Interim  Maturity  Date, or (c) upon
payment of such Advance in full (whether  pursuant to demand or otherwise).  Any
Advance  which is not paid in full on its Interim  Maturity Date or on or before
demand shall thereafter bear interest, payable upon demand, until paid at a rate
equal to two percent (2%) in addition to the "Prime Rate" (as defined below).


     The  Borrower  hereby  authorizes  the Lender to charge any  account of the
Borrower  maintained  with the Lender for any amounts due or payable  hereunder;
unless the Borrower instructs otherwise, all Advances made to the Borrower under
this Note shall be credited to an account of the Borrower  with the Lender.  THE
LENDER AT ITS OPTION MAY MAKE ADVANCES  HEREUNDER  UPON WRITTEN  INSTRUCTIONS  ,
WHICH  MUST BE  SIGNED  BY TWO NAMED  OFFICERS,  AND IN SO DOING  SHALL BE FULLY
ENTITLED  TO RELY  SOLELY  UPON  INSTRUCTIONS,  INCLUDING  INSTRUCTIONS  TO MAKE
TRANSFERS TO THIRD PARTIES, REASONABLY BELIEVED BY THE LENDER TO HAVE BEEN GIVEN
BY AN AUTHORIZED PERSON, WITHOUT INDEPENDENT INQUIRY OF ANY TYPE.

     For  purposes  hereof,  "Prime  Rate" means the rate of  interest  per year
announced  from time to time by the Lender called its prime rate,  which may not
at any time be the lowest rate  charged by the Lender.  Changes in the  interest
rate on any Advance  resulting from a change in the Prime Rate shall take effect
as set forth in each  announcement.  Interest  shall be computed  for the actual
number of days elapsed on the basis of a year consisting of 360 days,  including
the date an Advance  is made and  excluding  the date an Advance or any  portion
thereof is paid or prepaid.

     All  payments  hereunder  shall be payable at the  principal  office of the
Lender at 50 South LaSalle Street,  Chicago,  Illinois 60675, in lawful money of
the United States of America and in immediately available funds.

     The  Borrower  may prepay  without  penalty or premium any Advance  bearing
interest at a rate based on the Prime Rate. If the Borrower prepays, in whole or
in part,  any Advance  bearing any other interest rate or if the maturity of any
such fixed rate  Advance is  accelerated  upon  demand for payment  hereof,  the
Borrower shall also pay the Lender for all losses  (including but not limited to
interest  rate  margin) or  expenses  incurred by reason of the  liquidation  or
re-employment of deposits acquired by the Lender to make the Advance or maintain
principal  outstanding  at a fixed  rate.  Upon the  Lender's  demand in writing
specifying  such losses and expenses,  the Borrower shall promptly pay them; the
Lender's specification shall be deemed correct in the absence of manifest error.
Each Advance shall be conclusively deemed to have been funded by or on behalf of
the Lender by the purchase of a deposit  corresponding in amount to such Advance
and in maturity to such Advance's Interim Maturity Date.

     The Lender shall, and is hereby authorized by the Borrower to, endorse on a
schedule  annexed to this Note or  otherwise  record in its records the date and
principal  amount of each Advance,  the Interim  Maturity  Date,  the applicable
interest rate, and the date and amount of each payment of principal and interest
made by the Borrower with respect to each such Advance;  provided,  however, the
failure of the Lender to make any endorsement on any schedule shall not limit or
otherwise affect the right of the Lender to repayment of all Advances (including
interest thereon) made by the Lender to the Borrower.  The Lender's endorsements
as well as its  records  relating to Advances  shall be  rebuttably  presumptive
evidence of the outstanding principal and interest on the Advances.

     The Borrower hereby  represents and warrants to the Lender that (a) it is a
corporation  existing  and in good  standing  under  the  laws of its  state  of
incorporation and duly qualified, in good standing and authorized to do business
in each  jurisdiction  where the failure to so qualify would have a material and
adverse effect on its financial condition;  (b) the borrowings hereunder and the
execution and delivery of this Note are within the Borrower's  corporate powers,
have been duly authorized by all necessary  corporate action,  have received any
necessary  governmental  approval  and do not  contravene  or conflict  with any
provision  of  law or of the  charter  or  by-laws  of  the  Borrower  or of any
agreement  binding upon it; and (c) there has been no material adverse change in
the business, financial condition,  properties,  assets, operations or prospects
of the Borrower since the date of the latest financial statements provided by or
on behalf of the Borrower to the Lender.

     The Borrower  shall be deemed to have remade the foregoing  representations
and warranties each time it requests an Advance hereunder, except that (c) shall
be deemed to refer to the then most recent financial statements furnished to the
Lender.

     All sums  outstanding  under this Note shall be immediately due and payable
without  further  action of any kind on the part of the  Lender,  and the Lender
shall have and may exercise any and all rights and remedies  available at law or
in equity,  when the Lender demands payment hereof. Such sums shall be deemed to
have  been so  demanded,  and shall be  immediately  and  automatically  due and
payable without any action of any kind



on the part of the Lender,  and the Lender  shall have and may  exercise any and
all rights  and  remedies  available  at law or in  equity,  if any  bankruptcy,
insolvency, reorganization, arrangement, readjustment, liquidation, dissolution,
or similar proceeding, domestic or foreign, is instituted by the Borrower (or is
instituted against the Borrower and remains  undismissed for more than 60 days);
or if the Borrower shall  authorize such a proceeding;  or if the Borrower shall
become  insolvent,  generally  shall  fail or be unable to pay its debts as they
mature,  shall admit in writing its  inability  to pay its debts as they mature,
shall make a general  assignment for the benefit of its  creditors,  shall enter
into any composition or similar  agreement,  or shall suspend the transaction of
all or a substantial portion of its usual business.

     All notices,  requests and demands  hereunder  shall be deemed to have been
given or made when delivered by messenger or express delivery  service,  or five
(5) days after deposit in the U.S. mail, first class postage prepaid, addressed,
in each case:
(A) if to the  Lender  to 50  South  LaSalle  Street,  Chicago,  Illinois  60675
(Attention: Division Head, Mets I Division)

(B)  if to the Borrower to its address set forth below,
or to such  other  address  as may be  hereafter  designated  in  writing by the
respective parties hereto.

     THIS NOTE AND ANY DOCUMENT OR INSTRUMENT  EXECUTED IN  CONNECTION  HEREWITH
SHALL BE GOVERNED BY AND  CONSTRUED IN  ACCORDANCE  WITH THE INTERNAL LAW OF THE
STATE OF ILLINOIS  AND SHALL BE DEEMED TO HAVE BEEN  EXECUTED  AND  DELIVERED IN
ILLINOIS.  Unless the  context  requires  otherwise,  wherever  used  herein the
singular  shall  include  the  plural and vice  versa.  This Note shall bind the
Borrower,  its  successors  and  assigns,  and shall inure to the benefit of the
Lender, its successors and assigns, except that the Borrower may not transfer or
assign any of its rights or interest hereunder without the prior written consent
of the Lender.  The Borrower agrees to pay upon demand all expenses  (including,
without limitation,  reasonable  attorneys' fees, legal costs and expenses,  and
time  charges of  attorneys  who may be  employees  of the Lender,  in each case
whether  in or  out  of  court,  in  original  or  appellate  proceedings  or in
bankruptcy)  incurred or paid by the Lender or any holder  hereof in  connection
with the  enforcement  or  preservation  of its  rights  hereunder  or under any
document or instrument executed in connection  herewith.  The Borrower expressly
and irrevocably waives  presentment,  protest,  demand and notice of any kind in
connection herewith.

     BOTH  PARTIES  HEREBY  IRREVOCABLY  AGREE THAT ALL SUITS,  ACTIONS OR OTHER
PROCEEDINGS  WITH RESPECT TO, ARISING OUT OF OR IN CONNECTION  WITH THIS NOTE OR
ANY DOCUMENT OR INSTRUMENT  EXECUTED IN CONNECTION  HEREWITH SHALL BE SUBJECT TO
LITIGATION IN COURTS HAVING SITUS WITHIN CHICAGO,  ILLINOIS. BOTH PARTIES HEREBY
CONSENT  AND SUBMIT TO THE  JURISDICTION  OF ANY LOCAL,  STATE OR FEDERAL  COURT
LOCATED IN CHICAGO,  ILLINOIS,  AND HEREBY  IRREVOCABLY  WAIVES ANY RIGHT IT MAY
HAVE TO REQUEST OR DEMAND TRIAL BY JURY,  TO TRANSFER OR CHANGE THE VENUE OF ANY
SUIT,  ACTION OR OTHER PROCEEDING  BROUGHT BY THE LENDER IN ACCORDANCE WITH THIS
PARAGRAPH,  OR TO  CLAIM  THAT  ANY  SUCH  PROCEEDING  HAS  BEEN  BROUGHT  IN AN
INCONVENIENT FORUM.

     NO PROVISION OF THIS NOTE OR ANY RELATED  DOCUMENT OR  INSTRUMENT  SHALL BE
CONSTRUED  TO  REQUIRE  THE  LENDER TO EXTEND ANY CREDIT OR MAKE ANY LOAN TO THE
BORROWER,  OR TO  REQUIRE  THE  BORROWER  TO  BORROW,  WHETHER OR NOT ANY FEE IS
PAYABLE BY THE BORROWER IN CONNECTION HEREWITH. THE BORROWER CLEARLY UNDERSTANDS
AND  AGREES  THAT  THIS  NOTE IS A DEMAND  OBLIGATION  PAYMENT  OF WHICH IN FULL
(INCLUDING  PRINCIPAL,  INTEREST,  AND ANY OTHER AMOUNTS) MAY BE DEMANDED BY THE
LENDER AT ANY TIME IN ITS DISCRETION WITHOUT PRIOR ORAL OR WRITTEN NOTICE OF ANY
KIND, AND REGARDLESS OF WHETHER OR NOT AN ADVANCE HAS BEEN  OUTSTANDING  THROUGH
OR BEYOND ITS INTERIM MATURITY DATE.

                    CDW COMPUTER CENTERS, INC.
 
                      By: ______________________________________________________
                      Name:  Harry J. Harczak
                      Title:  Chief Financial Officer

                      By:  _____________________________________________________
                      Name:  Michael P. Krasny
                      Title:  Chairman and Chief Executive Officer

                      Address for notices:
                      200 North Milwaukee Avenue
                      Vernon Hills, Illinois 60061
                      Attention:  Mr. Harry Harczak, CFO

FORM 9640-B LARGE CORPORATE BORROWERS, UNCOMMITTED DEMAND LINE

                           CLOSING LIST AND MEMORANDUM


                            CDW COMPUTER CENTERS, INC
                             an Illinois corporation
                           200 North Milwaukee Avenue
                          Vernon Hills, Illinois 60061
                                (the "Borrower")


                           THE NORTHERN TRUST COMPANY
                             50 South LaSalle Street
                             Chicago, Illinois 60675
                                 (the "Lender")


                                 LINE OF CREDIT
                                 $25,000,000.00


                             Banker: Brian D. Beitz
                                 (312) 444-3987

                            Attorney: John A. Kelley
                                 (312) 444-7175

Description of Transaction:

     The Lender will increase to $25,000,000  its existing line of credit to the
Borrower.  [The  foregoing  description  is solely  for the  convenience  of the
parties and does not constitute a commitment on the part of the Lender.]

                             DOCUMENTATION REQUIRED

                   Rec'd -     Rec'd -   
 Item    Copies     Loan       Loan
Number  Required   Officer   Operating   Title of Document

  1.      The       ____       ____      Line of Credit Demand Note
        Original

  2.       2        ____       ____      Certificate - Borrowing Resolution
                                         and Incumbency


  3.       2        ____       ____      Certificate - No Amendment to Articles
                                         and Bylaws

  4.       2        ____       ____      Side Letter on Interest Rates


                                                                   June 30, 1998

CDW Computer Centers, Inc.
200 Milwaukee Avenue
Vernon Hills, Illinois 60061
Attn: Mr. Harry Harczak, Chief Financial Officer
     
Re:  $25,000,000  Line of  Credit  Demand  Note  dated as of June 30,  1998 (the
"Note") issued by CDW Computer  Centers,  Inc. ("you" or the "Company") in favor
of The Northern Trust Company ("us" or the "Bank")

Dear Harry,

     As you know,  the Note  provides  for loans at interest  rates as agreed to
from time to time between you and the Bank. You have asked for information as to
the rates we intend to quote.  Currently,  if a request  for a loan came in from
you we would expect to quote a rate  calculated  based on 30, 60 or 90 day LIBOR
plus 0.45%,  NY Fed Funds plus 0.45%,  or Prime minus 2.5% (but not less than NY
Fed Funds plus 0.45%), as appropriate for the amount and term of the advance.

     The Note is, of course,  part of an uncommitted  credit facility and we are
not obligated to make loans or to quote any  particular  rate. The Note gives us
and you the  flexibility to apply such interest rates as we may mutually  agree,
without  locking  either  party in to the  LIBOR or Fed  Funds  formulas  or any
predetermined spread.

     I hope this  information  is helpful to you.  Please contact me if you have
any further questions or comments.


                                      Best regards,



                                      Brian D. Beitz
                                      Vice President