Hello, I am planning on giving my iPhone4 to my wife who currently has iPhone 3G. From what I read I just have to backup her iPhone 3G...then restore the backup on the iPhone 4. But do I have to switch her iPhone 3G SIM card into the iPhone 4? We both are on AT&T. I'm going to give the iPhone 4 to my wife when the new iPhone comes out next month... Thanks.