One word - stability.

I'm a Windows GURU. But even on my system, and maybe more so because I mess with it so much, Windows crashes. It locks up, it fails and worst of all, it's annoying. You shouldn't have to hack the registry to make the balloons stop popping up over the system tray. In any case, I'm in the proccess of swithcing to the knoppix version of debian. I have it installed localy now, and i'm working on getting all my hardware working. I'm almost there. The only real drawback to linux as a whole is that gameing is pretty weak in comparison. There's plenty of games and some ports of games and a few that will run under Wine or WineX, bu in general, only a small portion of games run on linux. Older games are much better and more likely to run.