- Create a Backup folder on another drive will more free space such as (E:\Backup)
- Rename the Backup folder in %APPDATA%\Apple Computer\MobileSync\Backup to Backup1
- Open a command prompt and run: mklink /J %APPDATA%\Apple Computer\MobileSync\Backup E:\Backup
- Move the contents of %APPDATA%\Apple Computer\MobileSync\Backup1 to E:\Backup
iTunes will address the folder the same as it did the previous folder.