Currently testing Macbook 2.4Ghz - Aluminium (9400M),

Crysis - Low Detail, may lag even at DX9 (anyway... at low detail, u must as well play FarCry 1) 15FPS max
Crysis Warhead v1.1 (Couldn't install[keep getting error, Crysis doesn't support integrated] - Original one of coz)
COD4 - Mixture of high & medium (No AA) 35FPS max
Need for Speed Pro Street - Have to turn off the smoke and AA 30FPS max
Need for Speed Undercover - The only thing nice about the graphics is Maggie Q in the video clips, EA's fault. Not the MB.
Prince of Persia 2008 - Medium settings 28FPS max
Tomb Raider Legend - Full Detail 42FPS max
Tomb Raider Anniversary - Medium & High (No AA) 23FPS max
Tomb Raider Underworld - Couldn't make it even with medium graphics 18FPS max @ Medium
Far Cry 2 - Holy Shit, africa doesn't have trees and grass (low & medium detail) 17FPS max

If you are thinking of gaming with those Games i listed above. Please consider getting a desktop PC with a C2D 2.33ghz above & a decent 9600GT GPU or higher or get a Macbook Pro.

No point playing a game with low setting. You can't even enjoy what the game has to offer.

All the Framerates, i got it from using Fraps on Vista x86 Home Premium w/SP1. Vista is tweaked for performance and minimum RAM usage.
I have a MBA, Macbook 2.4ghz (Alu), Macbook Pro(8600M GT) all very close to me. And i work in an Apple Reseller Outlet. I'm proud to say, i'm still on windows! haha!