Mac Minis have received high praise as a music server. Particularly the metal unibody versions introduced in 2010 or so. The current model doesn't have a CD/DVD drive, so you would either need to buy an external one or buy a used model that has one. Also, it is rumored that new Mac Mini models are coming out in the next month or so. Might want to wait until they come out.
Another bonus of Macs is that there is some excellent playback software available for them, such as Amarra, PureMusic, Fidelia and others. Some are standalone programs, some integrate fairly seamlessly with iTunes.
Another bonus of Macs is that there is some excellent playback software available for them, such as Amarra, PureMusic, Fidelia and others. Some are standalone programs, some integrate fairly seamlessly with iTunes.