The first thing I would suggest is to not buy a Dell. However its up to you sir.
If you really want a Laptop with muscle I would advise one with an Intel T7600 2.33GHz dual core chip. Its the fastest mobile processor money can buy at present.
Get yourself 2 gigs of ram
and a Nvidia GeForce 7950 GTX 512mb graphics card.
Splash out, you want a laptop to play games, get a laptop that will play ANY game.
One thing you could do which I didn't do when buying mine, is get a 7200rpm RAID 0 Hard Drive... I had a standard 5400rpm drive...