Cannot install iOS 6 on my iPhone 4S and on my iPad 2.

Hey. I have an iPhone 4S and an iPad 2. Both non-jailbroken and the iPhone 4S is factory locked. So it only works on one carrier. I want to update to iOS 6 on both of them. It gets to almost end of the installation and then i get download error on both of them. I tried with iTunes to update it and when it gets to backup there it fails . It says : "Backup Failed. Re-connect iPhone and try again." or something like that. Any help please? I'm running iOS 5.1.1 on both , 16GB version on both of them and iPad is Wifi. Also running Windows 7 32bit. Help!