I just switched from 98SE, and LIKE XP pro.
Its older hardware as well, plus while I could see going to 7 I really don't want to go to 8, which means I have to look around for an old 764 license etc.
The point was to play a game on sale for $20, not spend a weekend and another $100 on upgrades.
I still play Diablo II LOD, and its not happy on 7, but I haven't spent much time forcing the issue. We have a dozen or so older games we still like to play, and eventually will have a couple legacy systems to play them on, just not at the moment.