After my post regarding only needing one version of Java, there were many follow up comments asking if the same is true for Microsoft’s .NET. Without getting technical and to best address the question for the masses the quick answer is no.
Unlike Java, .NETs versions are independent of each other, meaning an application can use .NET 1.1 even if .NET 2.0 is installed on a machine. While the versions are backwards compatible, ultimately an application designed using .NET 1.1 is going to be most stable running on (and more times than not require) .NET 1.1 be installed on the machine, even if .NET 2.0 is present.
So in a nutshell, to ensure application reliability, make sure the appropriate .NET library is installed on your machine to run it.

Jason Faulkner is the man who brings you our daily tips. He is based in Atlanta, Georgia.
Yeah, I found this out first hand. I uninstalled NET 1.1 because I had 2.0 and figured I didn’t need the older one. But I noticed my tv tuner software didn’t work anymore so I reinstalled 1.1 and that turned out to be the problem.