I have a FX 6300 and a GTX 750 Ti and I get 60 fps most of the time on a mix of mid-ultra settings so if you got a FX 6300 you would do pretty darn well. Although I do get some weird frame drops on certain maps, (like 2 maps out of 20 and only on particular servers) I think this could just be a game problem though and will be patched soonish.
If you scavenge around you could get the 6300 for 100 bucks.