I'll give it a week before you replace the PSU. If ATI recommends 600w I'd say go one better and get a 750, I had a 4870 and a 550w PSU and Sapphire recommended at least a 500w, it worked for a few days, got really stuck into Farcry one day and couldnt stop playing and then beooowwwwwmmmm, whole thing powered down. most PSUs cannot perform to their wattage spec as that's the perfect scenario, perfect amperage and voltage, temperature etc. think of it like the MPG on a car, they will always give you the best estimate.
the Earthwatts series is a quality PSU line. Because your PSU blew, it was most likely you did not have a quality PSU.