AMENDMENT NO. 1
                                       TO
                                CREDIT AGREEMENT

         Amendment  No. 1,  dated  June 21,  1999 (the  "Amendment"),  to Credit
Agreement, dated as of December 18, 1998 (this "Agreement"),  is entered into by
and among MLC HOLDINGS,  INC., a Delaware corporation  ("Holdings"),  MLC GROUP,
INC.,  a  Virginia  corporation  ("MLC"),  and MLC  FEDERAL,  INC.,  a  Virginia
corporation  ("Federal")  as  borrowers   (collectively,   the  "Borrowers"  and
individually,  a "Borrower"),  the banking institutions  signatories thereto and
named in Exhibit A attached to the  Agreement and such other  institutions  that
hereafter  become a "Bank" pursuant to ss. 11.4 of the Agreement  (collectively,
the  "Banks"  and  individually,  a "Bank") and First  Union  National  Bank,  a
national banking association, as agent for the Banks under the Agreement ("First
Union,"  which  shall mean its  capacity  as agent  unless  specifically  stated
otherwise).

                              Preliminary Statement

         WHEREAS,  the Borrowers,  the Banks and First Union desire to amend the
Agreement in the manner hereinafter set forth.

         NOW,   THEREFORE,   in  consideration  of  the  premises  and  promises
hereinafter  set forth and  intending to be legally  bound  hereby,  the parties
hereto agree as follows:

          1. Section 1.1 of Agreement.  The definition of "Ordinary  Course Sale
          ----------------------------
     or  Financing"  in  Section  1.1 of the  Agreement  shall be and is  hereby
     amended and restated to be as follows:

         ""Ordinary  Course Sale or Financing"  shall mean each of the following
         to occur in the ordinary course of business of any Borrower:

              (a) the sale  (including the  installment or conditional  sale) by
              such  Borrower of Inventory and Equipment so long as such Borrower
              receives  from such sale 100% of the fair market  value,  based on
              equipment  sold in the  ordinary  course and not in  distress-sale
              circumstances, of the Inventory and Equipment being sold;

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              (b) the  financing  (including  refinancing)  by such  Borrower of
              Inventory and Equipment  pursuant to this  Agreement and the other
              Loan  Documents,  so long  as such  Borrower  receives  from  such
              financing  100% of the fair market value,  based on equipment sold
              in the ordinary course and not in distress-sale circumstances,  of
              the Inventory and Equipment  being  financed;  provided,  however,
              that except to the extent  otherwise  provided in clause (d) below
              in connection with the simultaneous sale or financing of any Lease
              described  therein (i) any Lien  granted by such  Borrower to such
              lender in  connection  with such  financing  (which may be a first
              priority  Lien) shall not attach to any  property of any  Borrower
              other than the specific financed Inventory and Equipment, and (ii)
              the Debt of such Borrower to such lender in  connection  with such
              financing  shall be without  recourse to any Borrower  except with
              respect  to such  Borrower's  interest  in the  specific  financed
              Inventory and Equipment;

              (c) the sale by such  Borrower  of its  ownership  interest in any
              Inventory and Equipment  which has been  refinanced in an Ordinary
              Course Sale or Financing described in clause (b) above; and

              (d) the sale, financing  (including  refinancing) by such Borrower
              of any Lease providing for the lease of Inventory and Equipment so
              long as such Borrower receives from such sale or financing 100% of
              the Net Present Value of Lease  Payments for the Leases being sold
              or  financed;  provided,  however,  that,  except  to  the  extent
              otherwise  provided in the clause (b) above in connection with the
              simultaneous  financing of Inventory  and  Equipment  (i) any Lien
              granted by such  Borrower  to such lender in  connection  with any
              such  financing  (which may be a first  priority  Lien)  shall not
              attach to any  property of any  Borrower  other than the  specific
              financed Lease,  and (ii) the Debt of such Borrower to such lender
              in connection with such financing shall be without recourse to any
              Borrower  except with respect to such  Borrower's  interest in the
              specific financed Lease.

         Notwithstanding  the foregoing,  a financing  transaction  described in
         clauses (b) or (d) above shall still qualify as an Ordinary Course Sale
         or  Financing  even if the  Debt of such  Borrower  to such  lender  in
         connection  with such financing is with recourse to such  Borrower,  as
         long as the total of such recourse financing for all Borrowers,  in the
         aggregate,  is not more than 15% of the total amount of such  financing
         in effect for all Borrowers at any time under clauses (b) and (d)."

         2. Section  4.3(b) of Agreement.  Section  4.3.(b)  titled  "Landlord's
         -------------------------------
Waivers" shall be deleted and the following  shall be and is hereby  substituted
therefor:

         "      (b) Left Intentionally Blank."

         3. Section 5.1(c) of Agreement.  Section  5.1(c) of the Agreement
         -------------------------------
shall be and  is  hereby  amended  and  restated  to be as follows:

         " (c) Compliance Certificate. Within sixty (60) calendar days after the
         end of each of the first three Fiscal  Quarters of each Fiscal Year and
         within one hundred and thirty (130) calendar days after the end of each
         Fiscal  Year, a Compliance  Certificate  signed by the chief  financial
         officer or treasurer of Holdings."

         4.  Section  5.1(h) of  Agreement.  Section  5.1(h) of the  Agreement
         ----------------------------------
 shall be and is hereby  amended  and  restated to be as follows:

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         " (h) Monthly Accounts  Receivable  Aging Report.  No later than thirty
         (30) days after the end of each calendar  month for the first 11 months
         of each  Fiscal Year and no later than sixty (60) days after the end of
         each Fiscal Year,  an Accounts  Receivable  Aging Report  signed by the
         chief financial  officer,  treasurer or controller of Holdings.  In the
         case of the  first two  calendar  months of each  Fiscal  Quarter,  the
         information   contained  in  this  report  need  not  include  Buy/Sell
         Contract-Related  Receivables or AMC Receivables (less than or over 120
         days) as referenced in Exhibit F hereto."

         5.  Section  5.1(i) of  Agreement.  Section  5.1(i) of the  Agreement
         ----------------------------------
shall be and is hereby  amended  and  restated to be as follows:

         " (i) Quarterly Residuals Report. Within sixty (60) calendar days after
         the end of each of the first three Fiscal  Quarters of each Fiscal Year
         and within one hundred and thirty (130)  calendar days after the end of
         each Fiscal  Year,  a Residuals  Report  signed by the chief  financial
         officer, treasurer or controller of Holdings."

         6.  Section  5.1(j) of  Agreement.  Section  5.1(j) of the  Agreement
         ----------------------------------
shall be and is hereby  amended  and  restated to be as follows:

         " (j)  Quarterly  Inventory  Report.  No later than sixty (60) calendar
         days after the end of each of the first three  Fiscal  Quarters of each
         Fiscal  Year and no later than one hundred  and thirty  (130)  calendar
         days after the end of each Fiscal  Year, a Quarterly  Inventory  Report
         signed by the chief  financial  officer,  treasurer  or  controller  of
         Holdings."

         7. Section 6.3 of Agreement.  Section 6.3 of the Agreement shall be and
         ----------------------------
is hereby amended and restated to be as follows:

               " 6.3. Guarantees. Guarantee or otherwise in any way become or be
          responsible for indebtedness or obligations (including working capital
          maintenance, take-or-pay contracts) of any other Person (including but
          not  limited  to any  Subsidiary  of any  Borrower),  contingently  or
          otherwise,   in  any  amounts   that  would  exceed  an  aggregate  of
          $15,000,000 for all Borrowers."

         8. Exhibit D to Agreement;  Amendment to Security Agreement.  Exhibit D
         ------------------------------------------------------------
to the Agreement and the Security  Agreement  shall be and is hereby  amended by
inserting  the phrase  "Except for the premises  leased at 400 Herndon  Parkway,
Herndon, Virginia," at the beginning of Section 11(A).

         9. Representations and Warranties.  The Borrowers hereby affirm all the
         ----------------------------------
representations and warranties made in the Agreement,  including but not limited
to Article 3 thereof,  on and as of the date  hereof as if  originally  given on
this date.

         10. Covenants. The Borrowers hereby confirm that they are in compliance
         --------------
with and have complied with each and every  covenant set forth in the Agreement,
including but not limited to Articles 5, 6 and 7 thereof,  on and as of the date
hereof.

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         11.  Affirmation.  The  Borrowers  hereby  affirm  their  absolute  and
         -----------------
unconditional  promise to pay to each Bank and First  Union  National  Bank,  as
agent  under  the  Agreement,  the Loans  and all  other  amounts  due under the
Agreement  and any other Loan Document on the maturity  date(s)  provided in the
Agreement or any other Loan Document, as such documents may be amended hereby.

         12. Corporate Authorization and Delivery of Documents.  Each Bank shall
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have received (a) a certificate  signed by the secretary or assistant  secretary
of each  Borrower  certifying  all action  taken by each  Borrower and any other
necessary  Person to authorize  this  Amendment,  the  incumbency of the persons
signing this amendment,  and attaching any resolutions  adopted by each Borrower
in connection with said  authorization,  and (b) and such other documents as any
Bank shall require.

         13. Effect of Amendment.  This  Amendment  amends the Agreement only to
         ------------------------
the extent and in the manner  herein set forth,  and in all other  respects  the
Agreement is ratified and confirmed.

         14.  Counterparts.  This  Amendment  may be  signed  in any  number  of
         ------------------
counterparts, each of which shall be an original, with the same effect as if the
signatures hereto were upon the same instrument.

         IN WITNESS WHEREOF,  the parties hereto have each caused this Amendment
to be duly  executed  by their duly  authorized  representatives  as of the date
first above written.


                       MLC HOLDINGS, INC.


                       By: ______________________________
                       Name:
                       Title:

                       MLC GROUP, INC.


                       By: ______________________________
                       Name:
                       Title:

                       MLC FEDERAL, INC.


                       By: ______________________________
                       Name:
                       Title:



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                       FIRST UNION NATIONAL BANK, for itself
                       and as Agent


                       By: ______________________________
                       Name:
                       Title:


                       BANK LEUMI USA


                       By: ______________________________
                       Name:
                       Title:


                       RIGGS BANK N.A.


                       By: ______________________________
                       Name:
                       Title:


                       WACHOVIA BANK, N.A.


                       By: ______________________________
                       Name:
                       Title:


                       SUMMIT BANK


                       By: ______________________________
                       Name:
                       Title:



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                       KEYBANK NATIONAL ASSOCIATION

                       By: ______________________________
                       Name:
                       Title: