Get the 3570 Intel system. Hyperthreading rarely does anything for gaming, so put the saved money towards a sound card or something similar. Or a good cooler, something like a H80 Corsair would be good. You could also get a 2500K, they generally overclock about the same, and they can be cooled easier than a 3570 can because of Intels choice of awful thermal paste with the IVB chips.
PLEASE DO NOT GET A CRAPPY POWER SUPPLY!!!
You want at least a good branded 850W PSU, something like an AX850, or a Seasonic 860 or better. Higher wattage, and 80 Plus Gold or Platinum ratings are what you should be looking at. Power is super important for a long lasting high end gaming system.