http://www.newegg.com/Product/Product.aspx?Item=N82E16814131484
$139 after rebate for a 7870LE tahiti chip
just get that... its a great bang for buck and way overkill but at least it will still do very well at 1080p down the road if you buy a new monitor. plus you can more than likely sell the 2 game reward for like $20 which would bring your total investment to $119
the pickings get very depressing for the lower end non-tahiti 7870, the 7850 or 650ti, or even much lower for a 7770/7750 or gtx650... getting down to about $60 for the lowest end 7750/650.