Yeah, you'll be fine. Even with the rig in my sig, I rarely go over 300W.
Intel Core 2 Quad Q6600 @ 3.2GHz
4GB Mushkin DDR2 1000
Kingwin Mach 1 1000 watt Power Supply
Asus 4870 x2 graphics card
Gigabyte GA-EP45-UD3P motherboard
Cooler Master HAF 932 case
Samsung SyncMaster T240
3DMark Vantage:
X7241 (all settings maxed)
CPU: 11207/GPU: 7109