Well laptops generally aren't made for gaming and finding a good 'gaming' laptop would probably be somewhat difficult and expensive. AMD's are generalized as being better for gaming and Intel for apps mainly because of Intels bigger fatter pipelines, whereas AMD has smaller ones that can do more instructions per clock cycle than Intel...this is why you can see a 2.2GHz amd chip beat out a 3GHz Intel depending on the chips.
When it comes to ATI or Nvidia, well you'll get all sorts of answers on that and really it comes to personal preferences. It seems in my experience with a few different cards and reading posts on these forums that ATI always have driver difficulties, and generally I see more ATI based problems on this board...but then again that's just my Opinion. Like I said finding a laptop with a good onboard card would be hard, because laptops get really hot so they can only be 'so powerful' ya know? I don't know any particular laptops however, so just wait and see if someone indeed has some good suggestions.