I have a bunch of old cheap laptops in different rooms around the house connected to a wirless network all running some form of unix (actually OpenBSD and Slackware Linux). From my central PC Windows XP based I have the Oddcast plugin to Foobar2000 running. On one of the laptops I have Icecast running. I then stream Rhapsody or any music source around the house to any room all controllable through ssh sessions from any room as well. The biggest challenge is getting the sound synced between two rooms. You can get reasonably close by clever use of the unix tee program and the unix nc (netcat) and a whole bunch of |s.