NT "branch" releases: http://en.wikipedia.org/wiki/Windows_NT#Releases http://en.wikipedia.org/wiki/Windows_NT#Releases And that was: * NT 3.1 - Had Windows 3.

NT "branch" releases: http://en.wikipedia.org/wiki/Windows_NT#Releases http://en.wikipedia.org/wiki/Windows_NT#Releases And that was: * NT 3.1 - Had Windows 3.x type UI * NT 3.5 - Had Windows 3.x type UI * NT 3.51 - Had Windows 3.x type UI * NT 4 - Had Windows 9x type UI * Windows 2000 (NT 5) * Windows XP (NT 5.1 - XP x64 was 5.2 though) * Windows Server 2003/R2 (NT 5.2) * Windows Vista/Server 2008 (NT 6.0) * Windows 7/Server 2008 R2 (NT 6.1) * Windows 8/Server 2012 (NT 6.2) I remember NT 4 was used on the main server(s) at my highschool. I think it's safe to say, XP was the first consumer/"home" user version. Though, Windows 2000 (Professional) was used in corporate environments.