Sync Your iPhone’s and iPod’s Music on Two Computers
This MOST FRUSTRATING feature of the iPhone and the iPod is the inability to automatically sync your media on one computer and be able to manually manage it on another. If you try and sync (manual or otherwise) your iPhone or iPod on a guest computer iTunes will wipe all the media.
With a few small easy changes to the iTunes Music Library XML file you can then sync your phone (or iPod touch) with different systems.
Just make sure you backup the XML file before you start, but this solution works for me!
