iPhone not Syncing with iTunes

I was wondering if anyone could offer me some advice about troubleshooting an iPhone not Syncing with iMac with iTunes.

I have done a lot of basic troubleshooting on this problem, and I don't think the problem is the iMac or the iPhone. I think the problem is related to iTunes.

The iPhone is recognized by iPhoto, so I know the cable and OS connectivity with the device works. I tired all the suggestions on the web sites I checked, except delete and re-install iTunes. If I have to do this (i.e. delete and re-install iTunes), can anyone tell me a good way to backup the application and data before performing a re-install.

This problem has only been with this iPhone, my friend has had this iMac for years and used it with other iPhones. I am not sure if the Genius bar or online support is an option since this Mac is several years old and out of warranty. I guess if no one here can help me, I can post this on the Mac forum.

Sorry I don't have Mac model, or versions of OS or iTunes, but can tell you we checked if we had the latest version of the iTunes application.