Well, there's no such thing as ISA Server 2003... the current version is
2004. Seems silly, but I spend a lot of time in Asia and have seen plenty of
fake Microsoft products in the markets... you do in fact have ISA Server
2004, correct?
ISA Server 2004 will run on Windows 2000 Server SP4 just fine. You also need
IE 6 on the computer, and should apply
http://support.microsoft.com/default.aspx?scid=kb;en-us;821887 too.
I'm wondering if there's something wrong with your download -- is that the
demo you have? Maybe you could download a fresh copy from
http://www.microsoft.com/isaserver/evaluation/trial/ and see if that will
work for you.
Steve Riley
(e-mail address removed)