I was reading though Custom PC, and they did a lab test on about 20 PSU, Antec, Hyper, etc, etc, and only one PSU could handle everything they through at it. It was a Tegan true 480watt PSU (TG480-U01).
28Amps on the 12v rail, 48Amps on the 5v rail and another 28Amps on the 3.3v rail. Also fully BTX compatible with the ATX converter chucked in. The rest on the PSU's on test chickened out when approaching about 80% of there full load, this stood strong to about 500watt.
Heres a link, It's a steal for the price -
Here's another one, I'm guessing that it is a new version of the above PSU-