It will be close, but you'll be ok. The GTX470 is rated at ~220W. So two of them should be around 440W. To make the math simple, lets say 450W. Toss in another 100W for the CPU, and another 50W or so for the mobo/ram, and your looking at ~600W for the system. I'm sure as a Corsair it can output most of that 650W on the 12V rail, but having 50W of breathing room isn't that good of an idea.
If it were the card only how would it get that much power? 75W comes from the motherboard, and you get another 75W from a 6pin plug, or 150W from an 8pin. To get To get 366W you'd have to have two 8 pin plugs on the card, with the extra 66W coming from the motherboard. Can you link any GTX470 cards with two 8 pin plugs?
The max TDP of the GTX470 is 225W (I think). Most cases it won't go much over 200W. I think the GTX480 is 250-275W.