Before you do what it says on the link I put below, the first thing you have to do is connect your phone to your computer, open itunes and in the itunes top menu, you'll remove Store and you click on this authorization team. Once done open the link is below and at the end of the process, when you have first opened the itunes on the formatted computer, you have to go to the top of the menu, a Store and this time you have to Authorize this computer
15/03/2011 To date there is a free utility to move the contents of one pc to another or make a backup, called CopyTrans TuneSwift activation code is: TuneSwift-ACTIVE-ME