I recently bought a basic MP3 player for my daughter and want to move some music from my wife and I's iTunes and Zune files to Windows Media Player for her MP3 player to sync up to. But all my efforts to do so have failed. For the record, I'm running on Windows XP and do not have Windows Media Center.
If your iTunes files are in the iTunes format (.m4a or .m4p extension) you'll have to find a third-party tool to copy them. If you bought music from the iTunes music store, you'll have to remove the DRM protection to copy them. This Wiki has pretty good info and links to the JHymn project http://en.wikipedia.org/wiki/JHymn