Computer Do Over

Actually there are quite a few PCs that are as small or smaller than a Mac Mini. All of them are cheaper as well.
This one of them Acer Aspire.

Here's another called the Fit PC

Since you're using a wireless head unit, I'm not sure there will be a real difference in using any of them. I suspect not.
There's quite a few others out there as well. You could go with a full tower and just store it away using it as a server. Noise wouldn't be a factor in that setup. That takes the equation out of it having a fan or not.

For a server, I would opt for a more powerful full tower machine. And yes they can be whisper quiet as well if need be. Reason being you may in the future find more uses for it, other than just a music server.

I know many here are hell bent on a Mac, but there's always more than one way to skin a cat.

This is actually for our main computer, it just happens to store our itunes library and is in a bedroom. It goes to a Squeezebox which is in the living room with the music stuff.
We are getting fed up with our pc crashing, we seem to replace them every few years and so are considering the switch to MAC. We have limited desk space and so the mac mini is tempting, along with wireless accessories. We have a Samsung monitor to hook up to it. We also have small netbook as well.
Appreciate all the suggestions and comments - thanks!

For a main computer...I would just build one or have someone
to build one for me. Linux is another great option as an OS.

It's free and performs solidly. Virus protection isn't
really necessary with it either. My favorites are Linux
Ubuntu and Linux Mint. You can have a very fast, high
quality, stable computer with future expansion capabilities
not found in most manufactured computers.. that includes
Macs.

Plus no need to worry about all the proprietary stuff that
Mac users have to deal with either.
Good luck with your search.

See my earlier thread. In short. Im a mac guy (much prefer them), however when setup right windows sounds better (compared with two mac mini - so same hardware one running 10.6 one running bootcamp / xp). Using foobar, and ASIO there is simply no comparison once you tweak the buffers and settings in asio in windows. Its smoother, less grainy, with more depth. Mac is far from bad though.

If your unwilling to tweak or use asio, others here are right. mac is better. if your willing to tinker some, you can get much farther.

Id look at one of the fanless pc setups at mitxpc.com cheap, and no fan.

ps. Forgot to add. I have had much better luck with USB2 (m2tech) and firewire devices that are directly connected compared to wireless devices like the squeezebox.

If you plan on using the squeezebox... i doubt windows / mac matters at all since squeezebox is using the network not a direct connection.