I think you're best bet is to go with a Phenom II X4 or X6 (preferably one of the Black editions, 975 minimum) if you can get it cheap. The Phenoms are actually on par with the new Bulldozer and Piledriver chips when it comes to gaming and for the most part are superior in single threaded performance. An update the GPU to either and AMD 7850 or an NVidia 660 would probably also help.
If you do decide to upgrade your CPU then I'd do it fairly fast as the Phenoms are likely to be going out of stock soon and some retailers may even up the price due to short supply. Otherwise, I'd look for a whole new motherboard and CPU setup when the new Intel chips are released.








