I have a MacBook Pro and a iMac at home and would like to be able to add music or movies to my iPhone from either machine. I can do this with no issue with my 80gb Classic but it wants to erase and start over anytime I plug the iPhone in and try to do the same. I have manually manage music checked and I sync some photos and my applications on the iMac. If I uncheck the apps will it delete my apps from the phone? I suspect that is why it won't work on both machines...am I right?