First things first... If you hope to do more than some light occasional gaming with this system, rethink the idea of a laptop. For various reasons they make for horrible gaming systems.

That said, the more cores generally the better, and the more L2 cache, faster bus speed, and clock speed the better. However, if you want longevity, you're probably better off with a slightly slower quad core chip compared to a faster dual core. More L2 cache is probably more important than a faster FSB speed, but if you can get both, bonus.

The only real problem I see is that one system is an HP. Others will probably disagree with me, but if I can help it, I don't touch HP systems with a stolen 20ft pole. IMO they're just cheap, poorly assembled, garbage on the whole. If you buy a top end system it won't suck as bad, but the sub-$500 desktop systems aren't even worth using if they are given as a gift.

My opinions about shoddy HP quality aside, I'd say favor quad core systems over dual core all other things largely equal. Of course on a laptop, a quad core chip will likely suck the battery dry quite a bit faster if you ever get all 4 cores going full tilt. Such is the tradeoff you face with laptops. Faster performance requires more power, and that in turn drains the battery faster, so the laptop becomes less and less portable. So a very good idea would be to try and find some kind of stats on battery life if the system is under full load, since most of the info the manufacturers put out is if the system is sitting idle with every possible power saving tweak in effect. Then compare that with what you want out of a system, and decide if a laptop is really worth it if you can only use it 30-90 minutes without plugging it in.