What's your Operating System?

[Linux.Blue]

you can play more than you think, 99% of the games I owned can be played well on Linux, those were American McGee's Alice, doom 3, doom 3 ROE, Descent 3, Call of Duty, Call of Duty UO, Call of Duty 2, and I know Call of Duty 4 works, I just haven't gotten it going yet.
Penumbra Black Plague is really the only one, and I know that will be available for Linux someday.
but even if Linux couldn't play games, I'd rather deal with no headaches than several.

update: http://www.liflg.org - site with some games that you can play using the games specific loki instaler

http://www.winehq.org - a site that shows several games that work well under wine.

http://www.cedega.com - a site as well that shows several games; this you have to pay for; $15 I believe