>I had the same problem a few months ago. If I remember right, I think what I finally ended up doing was running the setup on the WCU disk (same thing as the prerequisites disk) by itself first - selecting all the the prerequiestes in the list - then when it finished - ran the setup in the vs.net 2003 disk.
The only way to achieve this installation was to use the Visual Studio .NET 2003 PreRequisites from May 2005. Then, when prompted, I had to manually select the sub directory of the PreRequisites in order to make this work.