Originally Posted by
Quintana
Personally I would save up the few extra dollars and get a 7850 instead, with a rebate you can pick one up for $189 or less.
That said none of those cards are going to run the game on ultra with 60 FPS everywhere. You'll probably get that performance in low population questing zones, some 5 man dungeons etc. In raids (especially 25 man) and in busy capital cities or questing zones you'll probably get between 30-50 FPS. The game is using an outdated engine, and is poorly optimized for even top tier systems.
Also the equivalent to the 6870 is a 560 (non TI), if you're dead set on that price range get whichever of the two cards is cheapest.