Although now discontinued, that version of the EarthWatts is a very nice unit made by SeaSonic - reviews for which can be found here http://www.hardwaresecrets.com/antec-earthwatts-500-w-power-supply-review/10/ and here http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story4&reid=35 (links to conclusion pages), I would think it'll work well with either graphics card
Although now discontinued, that version of the EarthWatts is a very nice unit made by SeaSonic - reviews for which can be found here http://www.hardwaresecrets.com/antec-earthwatts-500-w-power-supply-review/10/ and here http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story4&reid=35 (links to conclusion pages), I would think it'll work well with either graphics card