Low power consumption

Put this in the CPU section, but it could go in PSUs too, so apologies if anyone thinks I've hit the wrong section...

I'm trying to put together a home-built NAS, and I've already asked a load of questions about this, but I still have more! Basically, it looks like the best solution for me is a PC, probably running Linux, with a dedicated RAID controller and not much else. To that end I'm looking for information on the lowest possible power consumption that I can put together.

I don't need a multicore processor, nor do I need much in the way of performance. The motherboard will not need to support much - the RAID controller running on PCI, a gigabit NIC, a flash drive for the OS and that's pretty much it. I'd like the most efficient power supply I can, and I'd like every power-saving facility that I can - wake-on-lan, for example. Essentially, I want to have this thing running all the time and consuming as little power as I can possibly get away with. Low power consumption is much more important than budget. Ideally, it will be passively cooled, but that isn't a requirement.

There seems to be very little information out there about minimising power consumption. Can anyone help point me to some resources? Or give me suggestions for hardware to look our for?

Thanks Chookman...

That's still a 45W processor, though. I was thinking more along the lines of a mobile processor - the Intel Core Duo U2400 draws 9W (TDP) and the Intel Core Solo U1400 draws 5.5W (TDP). I'll need to dig around to see if I can find these...

Has anyone got any other suggestions, no matter how off-the-wall they are?

Cheers - Adam...

Nice one Chookman - that looks very useful.

Are there any other, even lower power systems out there to consider? Even the Athlon system outlined in that review uses nearly 40W idling. I probably wouldn't need much more than a mobile phone processor to drive a RAID controller and a gigabit ethernet controller, would I?