Run iTunes on an Old Mac 
Give your legacy Mac hardware a nudge into OS X with this XPostFacto hack and bring it into the digital music age.
Wait! Don’t throw out that old Power Mac or Umax clone; it just might be up for a little Mac OS X sprucing. Some of those old Macs will actually run Mac OS X, with a little help from an unassuming-looking control panel. Once you’ve Pantherized your old Mac, it will run iTunes quite nicely. While you won’t want to use the machine as a dedicated iTunes machine, it can make a great node on your network. You can throw it in your den and access your iTunes collection anytime, thanks to the Rendezvous sharing built right into iTunes.
I recently gave an old 7500 a G3 upgrade card from Sonnet ( http://www.sonnettech.com), a quad-port FireWire card, and a dual-port USB card (only $37, combined). Mac OS 9 ran rather snappily and the machine served quite nicely as a USB print server. Then I stumbled across a little something called XPostFacto (http://eshop.macsales.com/OSXCenter/XPostFacto/), which is open source and free.
XPostFacto is a little hack that brings Mac OS X, OS X Server, and Darwin to older, unsupported, and forgotten Mac models—those draped in the unfashionable beige of times past.
Warning
Before you think of giving XPostFacto a whirl, consult the compatibility chart at http://eshop.macsales.com/OSXCenter/XPostFacto/framework.cfm?page=XPostFacto.html#preparing. ...