The best "out of the box" solution I've seen so far is the Squeezebox or their new (and more expensive) Transporter plus any big chunk of storage (Windows/OSX/Linux) you can throw at the problem. The storage doesn't have to be near the stereo as the squeezebox or transporter has ethernet and WIFI connectivity.

http://www.slimdevices.com/

So I'm on board with you. I don't have one yet, but it's a planned upgrade.

Best,