Hi Rich,
I've been following this thread with great interest. I have my entire music and movie collection on an old PC with LOTS of terabytes running unRAID (a very cool linux based server). I've been using a SB touch to get at the music and a little HTPC for the movies (similar to yours, Atom 330/ION, power supply outside, windows 7). But now you have me thinking about using the PC as the music server too. Have you tried accessing the media over ethernet or wifi on your system, and if so, how does it compare to usb/esata? I'm using wifi with the touch right now and it's been surprisingly solid and sounds pretty good, but I have nothing to compare it to.