Sometimes while supporting products, it is very useful to know just what version/s of .NET are installed.
Found this tool just now shows you just that: Free DotNet VersionCheck Utility
If you’ve ever wanted a quick way to find out which versions and service packs of the .NET runtime are installed on a machine, or if you’re trying to resolve a ‘missing mscoree.dll’ error, then DotNET Version Checker is for you.
VersionCheck itself does not depend on the .NET runtime.
VersionCheck will also tell you whether you have the required Windows components to run .NET applications, and will prompt you with download locations if not.
Update: this page at Microsoft lists the downloads for .NET in the left menu bar.