VS 2003 builds for .NET 1.1 . It uses the .NET 1.1 (or 1.0) compiler, so could you write in .NET 2.0 won't be compiled. You will indeed need to use VS 2005 for all your .NET 2.0 stuff. And I believe that if the syntax is right you can just run it on IIS and IIS will JIT compilation of all your files. That is a new thing in 2.0, that you don't have to do pre compilation of your code behind files (which actually don't really exist in 2.0) For 2.0 compilers: if you installed .NET 2.0, you should have all the compilers in the .NET directory: C:\windows\Microsoft.NET\Framework\v2.0.40607 The minor version might be different on your system, so just check under the Framework directory for the right directory. Gidon