That processor OC easily and well and should handle 3.3-3.5ghz just on the stock cooler. You motherboard should handle it easily as well.
Forget about the HD4890 and choose between the HD5770 and the GTX 460.
It wouldn't be overkill if he OCs the processor and has a high resolution monitor.
Resolution is a good question actually as it is important when picking out a card so tell us your monitors native resolution.