amd will be cheaper to run smooth than intel would, since intel motherboard are pricey if you want intel i7 cpu and ddr3 support. you would save $200 or more with amd chip for similar gaming result, but for non gaming intel i7 would do better.
I had intel 2 duo 3ghz, geforce 8800 640mb oc (3years old setting) run okay in medium 1080p setting, cheapest way to run smooth in ultra setting, is the EVGA Geforce 460gtx which cost $250 performance better than 5850 very close to 5870, but is better due to far cheaper and quiter.
mugupo's comments