I use windows 7 for my gaming machine and I really love it. Linux on my laptop atm but distro hopping pretty often. On Ubuntu 8.10 atm but probably going back to slackware or arch.
The Dell tech who replaced my wifes hard drive in her laptop told her her old drive could not be formatted because you cant format vista hard drives.
(Before you ask, she wanted them to do it due to warranty integrity and i was at work.)
I deleted vista pretty quick and ran linux. I chucked windows 7 beta on it to test before rolling out to my main desk top and it deteced all hardware fine and ran it without issue.
Well, it can be made to never expire lol.
I usually try and keep my installs to a minimum and most app dont' require "installing" anyway. I only really use windows for games. My laptop running Linux handles the rest.
I never tried it myself to see if it would work. I though they must have been doing something wrong lol. i run it full time on my desktop, really liking it so far.