If you can wait for Black Friday at least, you will find some great sales. Even with laptops, there are some basic minimums you should shoot for if he wants to game.
~17"+ screen would be "better" for gaming, but it can be done on a 15.4". With the mobiles video chips you listed, you will still want something at least 1400x900 if you can. Obviously the better resolution - the higher $$$$. But I can't find anything for under $1k with that kind of resolution, that's powerful enough for gaming like I think he wants to - and not having "shared" video memory.
I noticed the asus Somebody_007 linked after i posted..
It is a ridiculously great deal, but it's heavy and thick. That to a 110 5'11" college student lugging it to class would be a major drawback.
just my $0.02