don't ever buy a PSU that isn't 80+ certified, you might end up destroying your PC with it... also, if you want to overclock, get a 600W psu, and you will thank me later, otherwise, that build looks quite nice :)
um. that is a 80+ bronze certified psu o.O but still, if you are overclocking ,i would recommend a 600W psu, just to make shuer you have the power needed :)
That should be good for you, That will be a sweet system you are getting and will last you many years :) and if you are running out of gaming performance in the future, just slap another 280X and you will be good to go for a few more years :)