It's not the wattage; very rarely, a PSU will support the wattage it is rated at. Cheaper ones tend to be worse, I remember a case where a 600W was only outputting 380W to 410W peak.
Righteous, do you believe the one I recommended would be enough? I think it would. They usually make good products, and that rebate is insane, but he can't do that.
http://www.newegg.com/Product/Product.aspx?Item=N82E16817341018
It's supposed to output at a continuous 630W with 80 percent efficiency at the least.
I'm also going to get the Rosewill challenger plus the Rosewill HIVE series 650W combo. For 115
The HIVE series is based off OCZ ZS platform, so it should be similar. And its modular.