i7-950 - no OC. 2x 5970 with heavy OC. the rest is minimal. probably only wc pump matters - 18W.
1000W is the minimum you can get, and YOU NEED A QUALITY ONE. a 5970 Heavy OCed = 450~460W (normal POC is 400W) or so. CPU at full load is 130W or wtv... Right there is over 1000W, than include HDD, DVD-RW, pump etc, it is WAY over 1000W. Even at 10% CPU usage, you are basically maxing your PSU 24/7
I'd go with 1200W if you want to OC your 5970s. At stock,you have to expect at least 350W full load each 5970... You can pull it off with normal OCs, but heavy OCs are pushing it