Neither the Radeon 9000 nor the Intel Extreme Graphics 2 are particularly fast for gaming, but I'd actually give the nod to the 9000 since it has its own video memory.
I would be steering clear of the Celeron Ms, and if possible the Pentium 4s as well. The former is just too slow (it'd make the 1.2 GHz G4 in an iBook look fast), and the latter tends to be confined to laptops that are thick and/or short on battery life.
As far as what's left, I'd say this: if the video performance isn't great, go for thin-and-light; if it is, extra bulk isn't much of a problem. You can technically get laptops that are both thin AND fast (Voodoo PC is a good example), but you invariably end up paying a lot.