Well, in summary Gaming laptops performance is function of two factors: CPU speed and Graphic card.
At the moment NVIDIA 9600M is pretty cool card, and Intel T6400 CPU or above should be fine.
With these combination it should be able to play 90% of the games on the Market. (27th-March-09)
New Graphic cards with even better quality/ low power consumption will land on shops very soon by August 2009, hope that will cause reduction in prices for gaming Laptops to some affordable level.
There are some good quality Gaming laptops on the market from Dell, and Acer etc and prices are dropping as of writing this response on 27th March 09. I would say laptop with NVIDIA 9600M Graphic card, and price tag of $800 or bellow will an excellent deal .