IRREVOCABLE PROXY AND LIMITED POWER OF ATTORNEY

     The  undersigned   stockholder  of  Allstar   Systems,   Inc.,  a  Delaware
corporation (the "Company"),  hereby irrevocably  appoints each of Ronald Dupler
and Gerald Birin  attorneys and proxies of the  undersigned,  with full power of
substitution,  to vote on behalf of the  undersigned all of the shares of common
stock of the Company  ("Company  Common  Stock")  which the  undersigned  may be
entitled to vote on the matters set forth below:

     1.   To approve the Asset Purchase Agreement dated as of March 16, 2000, as
          amended,  among the Company,  Amherst Computer Products Southwest,  LP
          ("Amherst   Southwest")   and  Amherst   Technologies,   L.L.C.   (the
          "Agreement"),  pursuant to which the Company will sell certain assets,
          as set forth in the Agreement, to Amherst Southwest.

     2.   To take any action to oppose any Acquisition  Proposal as such term is
          defined in the Agreement, other than the Agreement.

     This  Irrevocable  Proxy and Limited Power of Attorney is valid and binding
and is  expressly  stated and deemed to be coupled with an interest and shall be
irrevocable for a period of eighteen (18) months from the date hereof, but shall
automatically  terminate  upon the first to occur of (i) the Closing (as defined
in the Agreement) of the  transactions  contemplated  by the Agreement,  or (ii)
termination of the Agreement,  except for a termination by the Company  pursuant
to Section  9.1(c)(3) of the  Agreement or a  termination  by Amherst  Southwest
pursuant to Section  9.1(b)(3)  of the  Agreement.  This  Irrevocable  Proxy and
Limited  Power  of  Attorney  shall  survive  the  death  or  disability  of the
undersigned  and shall be binding on any  successor in interest to the shares of
the Company Common Stock owned by the undersigned.  This  Irrevocable  Proxy and
Limited  Power of  Attorney  shall  operate to revoke any prior  proxy as to the
securities  heretofore  granted by the  undersigned  with respect to the matters
described herein.

     This  Irrevocable  Proxy and Limited Power of Attorney shall be governed by
the laws of the State of Delaware.  To the extent (if any) the undersigned would
retain under law, regardless of the foregoing authorization and appointment, any
residual rights  inconsistent with the foregoing  irrevocable  authorization and
appointment,  the undersigned hereby  specifically and expressly (i) waives such
rights,  (ii) agrees  never to exercise  such rights and (iii)  agrees  never to
claim, as a complaint or a defense,  or otherwise assert that such authorization
and appointment are not valid or enforceable. The invalidity or unenforceability
of any provision of this  Irrevocable  Proxy and Limited Power of Attorney shall
not effect the validity or enforceability of any other provision.  To the extent
(if any) any provision  hereof is deemed invalid or  unenforceable  by its scope
but may be made valid or  enforceable by limitations  thereon,  the  undersigned
agrees that this Irrevocable Proxy and Limited Power of Attorney, shall be valid
and enforceable to the fullest extent permitted by law.

Signature:          /s/ James H. Long
                    James H. Long

Dated:              April 6, 2000