Somewhat off the wall solution: netbook w/ new HD as music server?
You can pick up a refurb 9/10" netbook for ~$200, spend less than $100 on a new 500GB HD and call it a day.
Example* config:
ASUS REFURB EPC900HDB-BLK003X Eee PC intel celeron m 353 / 1gb ram / 160gb hdd / 8.9" wsvga LED display / xp home / 0.3mp webcam (*refurbished product w/3 month warranty) from mwave.com
+
WESTERN DIGITAL WD5000BEVT Scorpio Blue 500GB 5400 RPM 8MB cache SATA 3.0Gb/s 2.5" internal notebook hard drive (Bare Drive) from mwave.com
*Please bear in mind, I didn't really try to put together anything special, just randomly selected two products to give you an idea.