iTunes will not overwrite the data on the iPhone, unless you have the option checked to do this. When the iPhone is plugged in and you select it in the device menu, the sync page comes up with the iPhone picture and pertinent information, such as OS, etc.
If you click the info tab, at the bottom in the "advanced" section, there are check boxes to tell iTunes to replace the data on the iPhone with what is on the computer. As long as these remain unchecked, the phone should only sync one way, from the phone to the PC/Mac.
08-10-2009 12:34 AM