This is what I'd get, if you want modular cables and want to power up moderate SLI rig:
It has 40A on the 12v rails and has 5 yr. warranty. I believe it's made by Seasonic, so you can't go wrong there.
Corsair 520W SLI Certified Modular ATX Power Supply - CMPSU-520HX
http://www.buy.com/prod/corsai...loc/101/203270716.html
If you want more power, but are willing to forgo modular cabling, than I'd go with the Corsair tx650w PSU that PurdueRy linked. It's a steal at $80 after the $20 MIR!!! It has 52A on the 12v rail and has 2 x 6+2Pin (so 6 or 8 pin setup for GPU cards) and also includes a 5 yr. warranty. You can decide, but I'd go with the Corsair tx650w PSU because of the more power. You just won't have the modular cabling.