That EVGA listed above is a middling unit at best and certainly not to be confused with EVGA's excellent high end lineup made by Superflower.
Power supply tier list:
http://www.tomshardware.com/answers/id-1804779/power-supply-unit-tier-list.html
No one is confusing a bronze rated power supply from HEC/Compucase with a gold one from Super Flower (at least they shouldn't be). My point is you don't have to spend an arm and a leg to have a little extra "insurance". As far as that particular EVGA unit, its fine for what it is:
http://www.jonnyguru.com/modules.php?name=NDReviews&op=... (500w model)
http://www.techpowerup.com/reviews/EVGA/600B/
http://3dgameman.com/reviews/1514/evga-600b-bronze-powe...
In addition if you look at user reviews from any of the e-tailers that sell it they are pretty positive (and its been out long enough for negative reviews to come in if it were crap). Regardless, you can get a 550w to 650w bronze power supply by a reputable company for a good price if you shop carefully. For a gaming rig I wouldn't go with less even if you could get away with it. Over time variables like an interest in overclocking the CPU and GPU or hardware upgrades may make those closer to the wire choices less wise. That said, I have a secondary PC with a Phenom II X4 980 BE and an HD 7850 2GB with an Antec Basiq 430W, but they're at stock speed. If it were my main gaming rig I'd go with a better PS (and I have - Cooler Master V650 Gold).