My Current system is: Mobo: MSI Platinium II LGA755/975X ATX CPU: Intel E6600 Dual Core all stock. 2GB DDR2 500GB WD SATA HDD GPU: MSI NX8800 GTS 320 PSU: Corsair 550W ATX12V V2.2 I'm a programming student as well as a gamer. I've gained a raise at my current job and have approx. 1500 USD that I could put down on a gaming/programming rig. I'm not very savvy at overclocking and I'd like to roll stock but have decent fps on current current generation games and gaming engines.
Depending on how much of a fan of upgrading you are I'd tell you to go AM3, because AMD will be sticking with that socket for a while.
The way I see it you should either "max" out what you have, go AM3 or go socket 1336 with a i7 920 (maybe they'll actually stick to that one for longer than just the six core that's coming out, but who really knows what intel's gonna do)
Obviously, upgrading what you have or going AM3 would be the cheaper options.