that gpu will hurt you at that resolution. You should be looking at the new 5850 or 5870, even a 4890 would be worth while spend over the 4870.
Peruse the review
here, it outperforms the 4870 by 40-60% in almost every game. But @ $400 maybe its not the best price/performance ratio. The
4870 x2's are cheaper right now and trade blows with the 5870.