I have a HP DV7, it has a 2.8 core 2 duo, 4gig ram and an Nvidea 9600 graphics card so it handles the games pretty well and they are priced pretty well to.
Honestly I run an A model Toshiba Satellite. I just overclocked the CPU a bit. I run Chrysis fine. I spent 1k on my laptop a year ago, not it runs for about $600. Only thing is, cooling isn't so great, so I bought a small desk fan that constantly blows into the hot air out vent. Keeps the laptop quite cool
I would go with alienware for sure, by far the bast computers i have ever used.