Well, it certainly appears to be powerful. Combined 3.3v and 5v is 300W. i'd say thats more than enough. As long as it can keep voltage levels consistant and puts out what it says it can, it should be all good. Let us know how it performs when you get it.
EDIT: one last thing. Do the nice name brand psus label themselves according to their max power or RMS power? I've noticed a trend with cheap stereo equipment when they claim to be 1000W systems, but it's really 1000W MAX power output when everyone else labels it with RMS power output.
Anyways, that site made sure to mention that that is the maximum power it can put out. I've never thought to check if other psus use max power or rms power.