At $550 an HD 4200 is pretty good (on a laptop, for god's sake)... I'd stick with that.
You can't get gaming laptops cheap, that's like asking someone to sell you a new electric hybrid car for the same price as a 5 year convertible. xD
And about the laptop Sole Signal provided, that laptop has an integrated Intel graphics accelerator... plus it's gateway... I don't think you wanna go with that one... (Intel graphics doesn't seem so nice)
But, like Dhsu and Lvl 99 said... you're better off getting a gaming PC rather than a LAPTOP.
Part of the reason I don't like laptops is that you can't really upgrade anything past the RAM. RAM's not gonna increase your gaming performance (much). You want something flexible, something that you'll keep upgrading without having to spend $550 every time you do so (because, lvl 99 said, gaming parts become quickly outdated). On a PC, you can just upgrade the parts for much cheaper. You wouldn't have to buy a new 8 GB RAM laptop in a year, just buy two more sticks of 2 GB RAM (which is much cheaper).