Won't OP still have awhile to wait for the next gen nvidia cards? Or did they catch up to AMD's release schedule? If open to AMD wait, otherwise I would say go with a 570. Also if my i7 920 was still more than enough for single GPU gaming on modern titles his 2500k will be fine...
Hmm,going out and buying last generation hardware doesn't seem a good idea.
Sell off that old 570 now while its still worth something and get some big horsepower in there.HD7950 or GTX670 would be better than loading up with two outdated cards.
Intel CPUs and AMD GPUs.
I'm an equal opportunity fanboy.