Trust me mate, you do not want an AMD processor. AMD has great graphics cards, but the processors, frankly, suck. My last laptop was an AMD processor and it was terrible at times. Intel dominates the CPU market. The i series (i3, i5, and i7) are great, but, I'll let you in on a secret, wait a bit, the new Intel CPU, code named Sandy Bridge, is, to put simply, amazing. A $300 card that can outperform a $1000 card?
Yeah, it will need a new socket though, but worth it for the extreme performance at very low prices.
Of course, should you not want to do that, just buy the best (intel) card you can get. The CPU market is quite small really when you think of it.