Bit of a bump to see if you got a laptop in the end?
I recently got a Acer Timeline 4810TZG that has a Intel SU4100 @ 1.3ghz, 4GB DDR3 Ram and a ATI Mobility HD 4330 512mb...
I've installed a few games on it to test it, it can run Dirt 2 at native res on low graphics always above 30FPS, GTA IV EFLC on 720p again all low at 20FPS+, it can also play Bad Company 2 at 720p also all low at 20+ fps, it's not the best but it helps you to see if the laptops you are looking at can play the games well..
If you want to play new games well then look for something with a GeForce GT 330M or higher..