Looking for a way to manage my Music Library

I’m looking to figure out the best way to manage my music library and be able to use the files on all of my machines.

My setup:  Windows Vista Business Edition Laptop, Windows Vista Business Edition Desktop, with a 500 gig NTSF formatted USB drive, a Mac OS X laptop, and Kubuntu 8.04 workstation.

I am currently using iTunes to manage things, but have contemplated using some other program to control everything.  Also I have shared out my Music folder and so far have mapped drives, but is there a better way to manage my Music so I can play things on all devices?

Thanks in advance