If you have an application that uses/needs .NET 1.1 then 2.0 and 3.0 are not
to be considered supersets or replacements for .NET 1.x
So if you where to delete version 1.1 then there is a good chance
the application that requires .NET 1.1 will fail. The same is true for later
versions.
Each version of .NET is usually installed along with the application that
requires it, so if you have all three or four versions, then chances are
that somewhere along the way you installed at a minimum 3
applications, with each of those 3 applications requiring and installing
it's own version of .NET
How to determine which versions of the .NET Framework are
installed and whether service packs have been applied:
http://support.microsoft.com/kb/318785
As for .Net 1.0 not being listed in Add/Remove Programs
http://support.microsoft.com/?kbid=938244
For a list of each version of .NET and where to download:
http://support.microsoft.com/kb/923100
Note: Disregard the title of the article.
Scroll down to method #1, step 4 for the download links
To sort out the confusion of the real Net Framework version numbers:
See: .NET Framework version numbers
http://blogs.msdn.com/astebner/arch...ersion-numbers-go-with-what-service-pack.aspx