[thingie2]

You might not even need that high, I'm only running off a 400W PSU that came in my case (my system specs are in profile) so it's up to you, you might need more than me as the 6600 is newer than my card, and the CPU is clocked slightly higher, but you shouldn't need more than about 450W i wouldn't have thought.

EDIT: Opps, didn't notice this is over a month old, I just used the related forums links at the bottom of the page