+1 to what ko888 said. Also did you consider witch PSU to get? We can help you with that also.
I suggest something around corsair 650-750w TX series(or HX for better quality). The 650w models have 52 amps on the 12v rails. If you are considering to overclock the CPU tu higher speeds and also your new gtx580 then i recommend the 750w for clearance and capacitor aging. (ou, there will be others witch will say 750w is too much)
Anyway, hope you get that nice 1920x1080 monitor soon