I think you are wise to start your search with the squeezebox line then, it's not something I use on mine but when I tried it I found it really easy.

Another advantage of the SB range is that the server runs on ReadyNAS (and others) so it's easy to have a solution where the iMac can be off and you still get 100% function. I am sure you can do this with other solutions, but SB really make it easy. Even the reasonably priced RadyNAS Duo has Squeezecenter installed right out of the box.

I wouldn't discount the Apple solutions either, I've had both Apple TV and Airport Express units in the past and both do what it says on the tin very well.

Cheers


Cris.