I had the same issue installing Reporting Services 2000 Standard on my Win2K3 SP1 + SQL 2000 SP4 box. I followed the instructions outlined in this MS document (
http://support.microsoft.com/?id=867872). Unfortunately, the instructions falter in steps L,M,N,O, and P in the IIS 6 section. This section discusses the
Report Server virtual directory in the default web in IIS. That step should read
"In the Wildcard application maps section of
Application Configuration dialog box, click
Insert.... Then browse to the DLL (C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322\aspn et_isapi.dll) and then click
OK." You can then click OK your way out of the dialog boxes. Once I did that, Reporting Services worked OK and I was able to go on and install MOM Reporting Server. I hope this helps.
-Hisham