Talk:Keeping two iTunes libraries in sync
From Mac Guides
Has anyone succesfully done this, with a wifi connection between their 2 macs?
Syncing with windows
One disadvantage of using this method is that only the songs will be in sync between OS X and Windows. The XML file contains various data such as ratings, play count, skip count, last played, etc.
There should be a way using Applescript/Automator to create a local copy of the Library XML file, edit the file (to go from ~/Music/ to the Windows My music folder) and then copy it over.