This program will list all .NET Framework version installed. http://blogs.msdn.com/b/astebner/archive/2008/10/13/8999004.aspx. .NET Framework 2.0 and 3.0 will not be listed as installed programs in Vista as they are components of the operating system. http://blogs.msdn.com/b/astebner/archive/2007/03/14/mailbag-what-version-of-the-net-framework-is-included-in-what-version-of-the-os.aspx.