Thanks for the quick reply. If you don't mind me asking: under which circumstances would I need to switch to a higher Watt power supply? Could you provide some example?
If you're going for two or more 580s or 670s you may need an 800W unit. Which 700W unit do you have in mind exactly? You want a good one from a brand such as Corsair, XFX, Seasonic, OCZ, Antec, PC Power & Cooling etc etc...