Find .Net versions installed

There are many ways to find out which versions of .Net you have installed on a specific machine:

1. Check programs installed on your machine through your Control Panel. Look for Microsoft .NET
2. Call Environment.Version from a .Net application.
3. Traverse your folder structure to %systemroot%\Microsoft.NET\Framework , and look at the folders available
4. Visit this website.   http://www.hanselman.com/smallestdotnet/
5. Check in your registry key for all entries under  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP