Well what do you mean with the "best" power supply? If it's quiet and powerful that you're after, but don't care about money at all, get the Enermax Whisper EG651P-VE. It's got 550W, plenty of overkill but it can handle anything (I mean ANYTHING) you throw at it...TBird 1.4 @ 2 GHz, 6 PCI cards, GeForce3 overclocked, 8 case fans, 4 X15 hdds, another 4 73LP 10K RPM hdds, CDROM/CDRW/DVD/Zip (probably all working simultaneously), USB devices up to wazoo........and it would barely be breathing hard. And with all that, it's spec'ed at the same noise levels as the rest of the Whisper family. Of course it costs $165 bucks, but that's the only drawback I see (it IS a fairly big one too).
Anyone actually have one of these monsters??