HD7770 is ok, but you have better choices in that price range.
6850/70 are faster cards especially 6870.
http://www.newegg.com/Product/Produc...n=6870&x=0&y=0
But this is the bestbuy, good cooling, performance~6870
http://www.newegg.com/Product/Produc...82E16814127593
and you can buy cooler,something like this will be fine,CPU speed is very important
http://www.newegg.com/Product/Produc...82E16835103065