For the setup you have listed I would recommend a 1000w-1200w. You could manage with a 800w but it would be running kinda hard at peak. wattage isn't everything though. Also make sure that you have enough amps on all of your rails. I'm running a Kingwin 1000w Mach-1 PSU w/ I7firstname.lastname@example.org / 5HD's / 2x GTX460 Hawks @ 1ghz. I have my pc running 24/7 with no hiccups.