I have been syncing my iPhone 4 with my Win 7 laptop but want to finally start syncing with my MacBook. I have copied over all of my music, movies, apps, etc... and authorized the computer. When I connect the iPhone to iTunes on the MacBook and try to sync, it tells me that all my data will be erased. I was wondering if I turn off auto sync, take a backup, sync with the MacBook then restore from backup, will I then be able to continue syncing with the MacBook or will my iPhone think that since the last time I synced I used the Win 7 laptop, all data must be erased again in order to sync with the MacBook? Thank in advance for the help!