Excellent choice for PSU, unless you plan on buying a 2nd GPU for xfire downstream.
Wife's build - i3-540, ATI 5670 and the corsair 400 W PSU. My system - i5-750 w/5770 GPU. Your max power will be under 300 W with a single CPU.
Would concur with shadow187 that a 5770 would be a better choice.
If you think you might xfire two 5770s later (Depends on games you play and your satisfaction with thoes games), then I would recommend a 500 ->550 W PSU. Ideally you would want the PSU at 60 -> 75% loaded when GPU is loaded. A 2nd 5770 would jump your power consumption from about 290 W to 390 W which would be too close to max 400 W.
Your system (w/single GPU) will only draw about 100 W for reading emails, surfing the web, general usage and only approach the 300 Watts while at max load. At idle = 25% - Good and 75 % at full load (w/5770) - also good. You will have enough headroom to move up to a single 5870 GPU with the Corsair 400 W.