When I first built my PC back in 2003 I had Windows 2000 and Slackware on it. I used Slackware most of the time, but I had Windows just in case. I would boot into it sometimes, mainly to keep it updated. Then once during Windows Update, it spontaneously rebooted and the registry was corrupted. So I just formatted it as ext3 and got the space back
I was never that much of a gamer and don't have any exotic hardware, so it wasn't a big adjustment. Now I couldn't imagine going back.