I looked into this unit, but for $900 with 500GB, you could get a cheap laptop and hang a external HD of it and get the added benefit of a multi-use machine.
I guess this is what I was trying to avoid, i.e having to turn on the computer to listen to music. As I understand the Music Vault, after all the music is loaded I can just use the Squeezebox remote to access the music stored on the vault/NAS. In my brief research of NAS setups that work in conjunction with the Squeezebox software, the Music Vault seems the easiest to setup since it is specifically designed for that purpose. Of course, the ease of use does appear to come at a price.