[4nic8tor]

You need to do one of two things. If you have it Jailbroke you can access the filesystem via TotalCommander and transfer the iTunes_Control (or something like that) folder that has all of your music to your computer's (Mac's) HD. If it is not then you can use a program called iPod Access for Windows (or iPod Access for Mac) and it will automatically import your music into iTunes from multiple iPods. If you use the copy method then you need to open iTunes and select File>Add folder to library and then select the iTunes_control folder. Make sure that you have it set to 'Keep iTunes music folder organized' in the preferences before importing so that it can change all of the messed up folders from your iPod to normal. Then both computers will have the same iTunes library but to sync with both it will need to erase and re-sync every time you switch computers.