My wife's laptop has winme on it... It hangs more than any other non-broken computer I've ever used. I had to let her go on a business trip with it "as is" because I couldn't afford to goof up before the trip, but when she gets back I'll probably put winXP home on it. I'd use win98SE but I'd rather not re-install the whole OS and applications, so we'll start by trying a winXP upgrade (after backing everything up of course...)
I game with a well tuned and reasonably clutter-free win98SE installation. It works great and I've seen uptimes of over a week with no stability problems, but I have noticed that when hosting AH H2H for more than about 12 hours there's a chance of the computer hanging. I don't know if this is a problem with AH or win98, but I had zero problems like this before I started hosting AH H2H arenas for extended periods of time.