Change Your iTunes Backup Location Using Directory Junctions

Using an Elevated Command Prompt:

C:\Users\Sean>mklink /J "C:\Users\Sean\AppData\Roaming\Apple Computer\MobileSync

\Backup" "D:\Backups\iTunes\Backup"

Result:

Junction created for C:\Users\Sean\AppData\Roaming\Apple Computer\MobileSync\Bac

kup <<===>> D:\Backups\iTunes\Backup

If you see the error "The syntax of the command is incorrect." you probably copied the command from a web page and edited it. The 'fancy' quotes need to be replaced with the standard ones on our keyboard.

http://www.theiphoneguru.net/2010/12/30/change-itunes-backup-location/