I'm trying to Sync my iphone 3gs on more then 1 computer. I have it selected to "manually manage music and movies" on my work computer, and when I try to select this when it is connected to my home pc it says the itunes library will be erased and synced with the home library. but since I have it set to manually manage music and movies, will it only erase it this first time? And will it not erase anything except movies and music? I'm able to sync my ipod classic on both computers by having this box checked, but I don't want to loose more then my music and videos in the process since I can easily re-copy those back to it.