G.skill ram 80-100$ depending on voltage, speed, and timings
PSU: 650 watt Corsair 70$
Case: HAF 922 (90$)
GTX 470, regular deals for 270$ or less.
Generic lightscribe sata OD 20$
Maybe 30$ on an Intel NIC (good for Wow in crowded areas).
That's 920$ total. IMO either pocket the cash, save for a new monitor/SSD, or upgrade to an i7-870, in order of sensibility.