I haven't visited here in about 5 years, since my last build, and everyone helped me out alot in here.
I've still got my 700W Seasonic PSU , noiseless, works like a dream, and it's still pushing my Q6600, 8800GTX vid card, Asus p5k deluxe mobo, and 4 gigs of crucial ballistix tracer memory just fine.
Plus 2 optic drives and 3 hard drives taboot.
You can't go wrong with seasonic, probably the best psu out there period.
And if you need some help go to johnnyguru3d.com, he'll tell you what's what.
If your running crossfire or sli, a 700 W psu will still do the job but to be safe you can grab 850W.
My seasonic 700w is 5 years old still working flawlessly dog.... best ps out there....even tho there are other good ones.
here's psu reviews from johnnyguru
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Review_Cat&recatnum=13
let me know what u pick o.k