I know that Squeezebox server (or whatever it is called now) can be installed directly on some NAS, meaning you won't need another computer (NAS is a computer, after all) for Squeezebox chain to work. I don't know the details of how to go about this, though (i.e., I'm absolutely no fucking help).
I personally like Dan's idea the best, especially considering how flakey Squeezebox can be with music library.