I moved to linux and stopped gaming a year ago. My life couldn't be better and I have so much free time now, it's great!
There are plenty of games that run in linux.
I have the old UT installed and it is great, still has a large community.
I recently installed Tremulous http://tremulous.net/
and it has been eating up alot of my time. Almost too much!
More good games from what I have heard:
Moar games: http://en.wikipedia.org/wiki/Category:Linux_games
UT screen shots: http://ubuntuforums.org/showpost.php...2&postcount=44