Some great PC games

Galactic Civilizations II
Really amazing game and an indie developed title that has taken off
[youtube]http://www.youtube.com/watch?v=6vzqgTDHKXY[/youtube]

Defcon Everybody Dies
Great but subtle graphics and addicting scary game play
[youtube]http://www.youtube.com/watch?v=XBweZkYYkyo[/youtube]

Darwinia Trailer
Amazing Indie title, rumored to be coming to 360 XBLA
[youtube]http://www.youtube.com/watch?v=ig_GYvmBHDQ[/youtube]

All of these games are worth checking out and each has a demo, just google it