The best place to get information about PSU's for a high-end system is HardOCPs PSU Forum:HardOCP's Power Supplies for Today's & Tomorrow's Computers:
The best quality PSU below the PCP&C, with high amps per line, tight regulation, and high efficiency at room temperature is the OCZ PowerStream 520W.
Here is a link to it at NewEgg:NewEgg OCZ OCZ520ADJ ATX 520W Power Supply
If you are not going to have an SLI system, I highly
recommend the Fortron BlueStorm 500W. I cannot say enough good things about this PSU. It is a fully compliant ATX 2.0, with dual rails, low dB noise, high amps per 12v1 & 12v2 lines (15amps), very high efficiency (~80%), high regulation (+/- 4% under load), sleeved cables, and runs for ~$91.00 at NewEgg:FSP Group (Fortron Source) AX500-A ATX12V 500W
BTW, before you start thinking that you have to have a 500W PSU just because the MB is going to be SLI-capable, I would suggest calculating exactly how much power you really need first, adding up the CPU, video card, Optical drives, hard drives, case fans, sound cards, etc, using this:takaman's Power Supply CalculatorHOW TO BUY A PSU (or how to determine if your old one is up to it)