You could do that, it probably would work but I don't know what you would gain in real terms over getting a Rpi or one of the plug in computers etc.
The other option (which actually I had working quite well) is to use an O2 Joggler. I had it running as an MPD server for a while but couldn't get good audio out of its analogue out. But you could use a USB audio bridge for that. It has one external USB port. Atom CPU, 4G flash etc and fanless. There are another couple of internal USB ports (one requires some soldering and the other holds the wifi radio, but it has ethernet as well)
Typically they go for £50 or so on ebay (their eventual RRP new) and both Android and Ubuntu builds exist.
Plus you get a touchscreen for local control of your music.
My Joggler is just a front end now for my media PC, running Android and MPDroid and the XMBC remote.