在计算机上运行.net的许多版本

I'm curious about the various versions of .net. We have an environment where we've developed applications in various versions (1.1 and 2.0). Now, I'm trying to get the 'go ahead' for developing in 3.5. The biggest issue is whether or not these versions will play nicely together on the same installation of IIS. Another caveat is that I'm developing on Windows XP with Visual Studio 2005 and IIS 5.0. The applications will be running on windows server 2003 and using IIS 6.0. From what I have seen, it looks like each IIS virtual directory can set its own specific version of .net. Shouldn't this be enough that the varied applications using the varied .Net versions not affect one another?I'm curious about the various versions of .net.