I don't know much about power supplies and what not, how do you go about figuring out what amperage is needed for the graphics cards? Here are the stats for the 650 Watt ps:
PC P&C is considered the best, they are expensive though. Silverstone, Seasonic and OCZ make very good psu's at a decent price. Either of the ones you've chosen will work. You can check your requirements at http://extreme.outervision.com/psucalculator.jsp
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