QUOTE (jjtwo @ Sep 15 2011, 04:49 AM)
The music sync is one way - computer to iphone.
The exception is itunes purchases. Authorize/sign into your account on your computer, do not sync, click File>Transfer Purchases.
Besides what mentioned above, I like to share you a page reviews about how to transfer iPhone to PC or Mac
, which included transferring iphone contents to computer.
Hope that work you a big favor.
Officially you can only transfer music that you used your iPhone to purchase, from your iPhone to your PC, so you can back it up.
That said if you use google to search I'm sure you will find a program that will reveal the files on your phone and enable you to transfer - I've never needed to use one so have no recommendations, but it is possible with the right software.