We have a production server running Windows Server 2003 x64. There's a known issue with IIS on Windows Server 2003 x64 where the ASP.NET tab does not show up. I have a manual tool to switch my websites back and forth between 1.1 and 2.0. If you're not aware of this particular issue already, you probably won't be able to help, so please don't try.
If you know about the issue, great! It's worked well enough for us to be able to switch between 1.1 and 2.0, but now I have no way to switch to 3.5, and the previous tool we used isn't working. How do we manually configure a site for 3.5?