In average ther is just every second OS from MS that is worth to install if you look back in history.
If we look at the Window's OS the history is like:
I have left out the DOS era.
* "Windows 3.0" (not so long living and just more and less the first real commersal Windows OS)
* "Windows 3.1" The first real Windows Good in my View
* "Windows 3.11" Just a upgrade of Windows 3.1 bur with network integrated in the Windows level (no need to use a dos network driver) Good in my View
* "Windows 95" A new built OS but not complete yet
* "Windows 98" Good in my View
* "Windows 98 SE" Good in my View but realy just a little more then a servicepack
* "Windows Millenium" Whay
last scream on the 16-bit arcitecture
* "Windows NT 3.1" (first try) in NT
* "Windows NT 3.5" (Just server OS) Good in my view as the first 32-bit Server OS
* "Windows NT 4" Good in my view
* "Windows 2000" Just a first try to the XP arcitecture not a ready OS
* "Windows XP" Good in my view
* "Windows 2003" (Just server OS based on XP) Good in my view but only as server OS
* "Windows Vista" Whay
* "Windows 2008" Good in my view but only as server OS
* "Windows 7" Good in my view
* "Windows 8" ? Lets see