For the Server component we made asp.net v2.0 version which you can use.
for the Enterprise and Portal components if i remember correctly you can max have v1.0.3 running.
Please note that we highly recommend to upgrade away from 2003, as all the security flaws of the past 1 to 2 years are simply wide open op 2003.
Thank you Marco for recommendation but this is our special purpose server for older apps.
To be specific, server works fine both on 9002 and 9003, the main website on 9001 does not work. I hoped accessing the source code and compiling under .NET 4 may solve my problem but I realized that it is private.