Stiffs :
Why not to a 750watt or 1000? a 550watt is pretty similar. i have the money, is there any better you could recommend?
After a certian point, more watts is not better.
The 80 Plus rating on power supplies is an efficiency measurement, at 50% wattage load they can opperate at x% efficiency. Well when you get down to 20% load then your efficiency can really drop. Thus on a 1000w psu, when not gaming you will only use 120-150w of power and thus use far more electricity then say a 600w unit.
Not to mention that even 750w is more then what is needed for any new generation GPU (outside of some off-beat AMD ones).
There is no point to pay more for soemthing you wont use, wiggle room and future growth are very good to account for, but at a certian point it is sitll wastefull spending.