Quiet computer

[David King]

I am looking for a small computer that is silent or very quiet to sit  
in a home office.

It will be functioning as a server, and will need space for two  
ethernets (although preferably two ethernets and one wireless card, I  
can rig up a cheap access point instead), and two hard drives  
(although one can be external firewire or USB if necessary). It  
doesn't need a graphics card, although it wouldn't hurt, and here's  
the hard part: I would like it to be at least dual-core.

I see http://www.tranquilpc-shop.co.uk/, and they are pretty  
impressive, but most of the processors are VIA and don't go up to two  
cores (unless I missed something).

It's replacing my very aged 350 mhz server, which I've had for so  
long because it's so quiet.

So does anyone have a favourite vender of silent/very quiet PCs?