I have an IBM Thinkpad A21p (old laptop), so it isn't much of a gaming machine, though occasionally I'll play some Q3-based games on it. I mainly use it for web browsing and instant messaging. I also use it for music and video and sometimes DVD playback on road trips (15" screen on $175 used laptop > 7" screen on $220 portable DVD player
). I use Ubuntu on it, but sometimes use Windows XP as well.
For a better gaming experience, I use my HP (Radeon X1600Pro) PC, but I don't play many PC games (I mainly play games on the Wii).