I've seen some people here asking how to sync with their home and work computers without having to erase the iPhone. This is simple. Copy your ~/Music/iTunes/iTunes Library and ~/Music/iTunes/iTunes Music Library.xml to a flash drive at home and bring it to work. Then copy those files to the same location on your work computer. Then launch iTunes. You'll notice all the music you have at home show up, but it's ALL missing. This is okay. Just delete it all in iTunes. Then drag your ~/Music/iTunes/iTunes Music folder onto the iTunes icon to get all your work music back into iTunes. Now you can sync with both computers because iTunes thinks it's the same computer. Nice. I hope this helps some people who may not know about this trick. It's working for me. EDIT: This is important. Make sure you've enabled "Manually Manage Music and Videos" in the iPhone tab in iTunes. If you have it auto-sync I'm pretty sure it will replace the music which would defeat the purpose of this trick.