AMENDMENT NO. 1
                                       TO
                          VOTING AND SUPPORT AGREEMENT

          This Amendment to Voting and Support Agreement (the "Amendment") dated
as of April 6, 2000 is entered into between Amherst Computer Products Southwest,
LP, a Texas  limited  partnership  ("Amherst  Southwest"),  and  James  H.  Long
("Long").

                                   BACKGROUND

          A. Amherst Southwest and Allstar Systems, Inc., a Delaware corporation
("Allstar"), have entered into an Asset Purchase Agreement dated as of March 16,
2000, as amended (the "Asset  Purchase  Agreement"),  and Amherst  Southwest and
Long have  previously  entered into a Voting and Support  Agreement  dated as of
March 16, 2000 (the "Voting Agreement"). Capitalized terms not otherwise defined
herein shall have the meanings assigned to them in the Asset Purchase Agreement.

          B.  Amherst and Long desire to make certain  amendments  to the Voting
Agreement to provide for Long, in addition to voting all of the Majority  Shares
in favor of the  Asset  Purchase  Agreement  and the  transactions  contemplated
thereby,  to (i) vote all of his Majority  Shares against any other  Acquisition
Proposal  or any other sale or exchange of assets,  lease  transaction,  merger,
consolidation,  other business combination,  or corporate reorganization,  other
than that contemplated by the Asset Purchase  Agreement,  and to (ii) execute an
irrevocable proxy whereby he appoints Amherst Southwest's designees as attorneys
and proxies,  with full power of  substitution,  to vote on behalf of Long,  the
Majority  Shares  of  which  Long  may be  entitled  to  vote  in  favor  of the
transactions  contemplated by the Asset Purchase Agreement and to vote on behalf
of Long, the Majority Shares of which Long may be entitled to vote,  against any
other Acquisition Proposal, whether solicited or unsolicited.

          NOW,  THEREFORE,  in  consideration  of the  premises  and the  mutual
promises herein made, Amherst Southwest and Long agree as follows.

                                   AGREEMENTS

          1.   Status of the Voting Agreement.  Except as specifically set forth
herein, the Voting Agreement shall remain in full force and effect and shall not
be waived,  modified,  superseded or otherwise affected by this Amendment.  This
Amendment  is not to be construed as a release,  waiver or  modification  of the
terms, conditions,  representations,  warranties,  covenants, rights or remedies
set forth in the Voting Agreement, except as specifically set forth herein.

          2.   Amendment to the Voting Agreement.

               (a)  Section 2(a) of the Voting  Agreement  is hereby  deleted in
its entirety and replaced by the following:





                    "(a) Majority  Approval.  Long  agrees  to vote  all of  the
               Majority Shares in favor of the Asset Purchase  Agreement and the
               transactions  contemplated thereby, and agrees to vote all of the
               Majority Shares against any other Acquisition  Proposal,  whether
               solicited or unsolicited. In addition, immediately upon execution
               of this Agreement,  Long further agrees to execute an irrevocable
               proxy in the form attached as Exhibit A."

               (b)  Section 3 of the Voting  Agreement is hereby  renumbered  to
become Section 4, and all terms  previously  stated therein shall remain in full
force  and  effect,  and a new  Section  3 of the  Voting  Agreement  is  hereby
inserted, which shall read as follows:

                         "3.   Indemnification.   Amherst  Southwest  agrees  to
               indemnify  Long for one-half of any costs  incurred in defense of
               any lawsuit filed against Long complaining of Long's execution of
               the  proxy   provided  for  under  Section  2(a)  of  the  Voting
               Agreement, but in no event shall Amherst Southwest be required to
               pay  more  than  $100,000  in  the  aggregate  pursuant  to  this
               indemnification provision."

               (c)  The  prior  Section  4 of the  Voting  Agreement  is  hereby
renumbered to become  Section 5, and all terms  previously  stated therein shall
remain in full force and effect unless amended hereby.

               (d)  Exhibit A attached  to this  Amendment  shall be attached as
Exhibit A to the Voting Agreement.

          3.   Effectiveness  of  this  Amendment.  The  effectiveness  of  this
Amendment is contingent  upon the execution of Amendment No. 1 to Asset Purchase
Agreement  dated as of April 6, 2000 by and  among  Amherst  Southwest,  Amherst
Technologies,  L.L.C.,  a  Nevada  limited  liability  company  ("AmTech"),  and
Allstar.  This Amendment shall automatically  terminate if the escrow payment or
the  expense  reimbursement  therein  required  is not  timely  made by  Amherst
Southwest.

          4.   Representations  and  Warranties  of  Entities.  Each of  Amherst
Southwest  and Long  represents  and warrants that its  execution,  delivery and
performance  of this  Amendment is duly  authorized and that this Amendment is a
legal,  valid and binding obligation of such party in accordance with its terms.
Long further  represents and warrants that  sufficient  approval of the board of
directors  of Allstar had been  obtained  for the Voting and  Support  Agreement
dated as of March 16, 2000 between  Amherst  Southwest,  and James H. Long,  and
this Amendment,  in a manner  sufficient to make the  restrictions  contained in
Section  203  of  the  Delaware  General  Corporation  Law  inapplicable  to the
transactions contemplated by the Asset Purchase Agreement, as amended.

          5.   Counterparts.  This  Amendment  may be executed in  counterparts,
each of which  shall be  deemed an  original  and both of which  together  shall
constitute one and the same instrument.

          6.   Governing Law. This Amendment  shall be governed by and construed
in  accordance  with the domestic laws of the State of Delaware  without  giving
effect to any choice or conflict of law  provision or rule (whether of the State
of Delaware or any other  jurisdiction)  that would cause the application of the
laws of any jurisdiction other than the State of Delaware.

          7.   Further  Assurances.  Long  agrees to take all action and execute
any  documents in his capacity as a  stockholder  of Allstar  consistent  with a
request  by the  Company to its  stockholders  generally  to  approve  the Asset
Purchase Agreement, including execution of a ballot card.

          IN WITNESS WHEREOF, the undersigned have executed this Amendment as of
the date first above written.

                                        AMHERST COMPUTER PRODUCTS SOUTHWEST, LP

By:      /s/ James H. Long         By:  /s/ Gerald Birin
         James H. Long                  Gerald Birin, Chief Financial Officer