MSI, Asus, and Gateway all have pretty good options for under 1500.
For Asus I know that BestBuy just got in the G51/G71VX models in, with the GTX 260m videocards... but, the drawback with them is the screen resolution, and they're bulky. They're solid though, and Asus will make higher screen resolution models that will go to places like Newegg soon.
MSI has some nice affordable models with 9800m GS or mobility 4850s. They'll be a touch less powerful than the Asus models, since Asus just started their GPU refresh to the GTX260, but MSI makes more lightweight and less bulky laptops. They do have some keyboard flex though, which makes me prefer Asus despite their extra bulk.
Gateway likes to put out a decently configured, but huge 17" model. While I would consider the P-7805u ugly as sin, for the price its hardware is pretty darn good. I don't think Gateway's got its refresh to the GTX260M GPUs, so they're still running with 9800m GTS cards, which are just a bit slower.
And finally, if you can consider going a little bit over 1500, Clevo makes the best gaming laptops, IMHO. A Sager NP8662 would run you about 1600 bucks after you make the necessary minor upgrades to the base config... which is a little expensive compared to the Asus. But, it'd be a machine without any cut corners to get costs down... just a solid build, with solid hardware. The cooling solution in this model has always been very good...
If it was my money, I'd wait a little bit for an Asus G51VX with a high res screen. But, its possible to make an arguement for any of these.
Keep in mind, anything with less than a 9800m GS is going to perform like crap. This is why I didn't mention brands like Dell, HP, Sony, Samsung, and so on. I left Alienware out because if you're buying a m15x its only because you're too stupid to buy a Sager NP8662.