If your iPod is formatted for OS X there is no way to convert the file system to Windows format (FAT32) without a complete format. All the data on the iPod (music, files, contacts, ect.) will be lost. But it is OK! You have all that stuff on your eMac. After you have formatted it with the newest iPod Updater for Windows, found at
http://www.apple.com/ipod/download , you can go home an put all your music back on.
Another good thing to remember is that whenever an update is available for the iPod you must update it on a Windows PC. For example, if I tried to updated my Windows formatted iPod on my Mac so that I could, for example, use the new Podcasting feature, the computer will try to format the iPod to the OS X file system. All iPod updates from now on must be made on a Windows PC. Hope this helps.
- Lou