Vista is what drove me to Mac OS, Windows 7 does not seem like much of an improvement in my limited testing. I hated the fact that Microsoft would just move everything around for no good reason, so I had to relearn to do everything I could do in XP. I managed with Dos v3.3 -> XP.
Strangely enough, Windows 3.1 sure seems a lot smaller and snappier than Windows 7...