Hi,
My sister plays swtor with a geforce 460 @ 1650x1050 and it runs everything on high,but she does say it runs better on her bf's 6870..i'd go for the best you can afford to,but both are viable for decent gameplay, pvp can be laggy but I think thats the games/bioware's issue more so. Illum is a joke to say the least lol.
I mostly pvp so that's where I want the most performance. Think I'm leaning towards a 6950 or The 7870 if that turns out any good.