290s are good
btw https://docs.google.com/spreadsheet/ccc?key=0ApyK2Y6kDbKidEN2LXpCdDBTRlZPMUN6VHRWc2ROUUE&usp=sharing#gid=0

but if you want take this seriously go for dedicated mining rig

depends how much you play but anyway... swaping from game to mine and back...