In response to a bunch of posts here...
I myself own a sub-optimal "gaming laptop", it's only about 1,5 years old though, but it's still alive and kicking pretty well.
I have a Vaio AR 17" 1440:900, Intel Core 2 Duo CPU T7250 @ 2.00GHz, 2 GB RAM with NVIDIA GeForce 8400M GT (256MB dedicated VRAM). I can play most modern games on minimum or medium settings with little lag. What bottlenecks it though is actually the processor, and especially the RAM (hence all the lag in games). So, I recommend getting either more RAM, or a laptop that's fully compatible with XP so you can downgrade for gaming. While DX10 is nice and all, I have found that running games on medium in XP works out a lot better for me than running on min in Vista and still getting lag. I'm sure Win7 eats up about the same amount of RAM as Vista, as well.
I also recommend getting a laptop with a dedicated GFX card and not integrated one, because many recent games refuse to run on integrated gfx even if the card "technically" has enough vRAM to run it.
Overall, I'm very satisfied with my Vaio thus far, but seeing how the author seems to hate Sony now, maybe that's not an option. One thing I do like about this one is that it's got a fairly powerful fan and enough space for all the hardware, I have never had it overheat even in 30 degree 100 humidity weather, much less shut down due to overheating.
Acer makes good laptops for the price, but if you're getting one of the more powerful ones, a laptop stand with an extra fan is pretty much a must to keep the thing going.
Toshiba is a decent solution for durability, at least until recently (can't tell since I haven't used/seen their products in the last 2 years or so, but they do have a good reputation).
Never get a Dell. It's an overpriced PoS which heats too much and burns just as easily.