I'm rocking a GTX 550ti and it can run practically everything max settings so a GTX 660 will be fine for the long term aswell
Yeah I'm currently using an GTX 550 Ti too ( as you can see in my profile ) but it lost much of it's power , and with the upcoming games ( crysis 3 , etc. ) I think I need a new card , and the GTX 660 is fine for those I think.