I have never used Windows 7 or Vista.
XP will probably be the last MS OS on my PC, although I can see myself using a newer MS OS at work.
When I buy a new PC, I'll install Linux and not use Windows, even if it comes with it pre-installed. I don't think I'll make much of an effort to buy a Windows-free PC because it might be handy for using Windows DLLs, fonts and enable me to legally download lots of stuff from the MS website to improve compatibility.