You can update the following devices to iOS 5

• iPad and iPad 2

• iPhone 3GS and iPhone 4

Note
In order to update a device to iOS 5 you must first restore it with the latest version of iTunes. Before restoring the device, iTunes creates a backup from which it restores the device. Do not interrupt this routine.

Follow a few easy steps to prepare your device for successful restoring:

Make sure that the latest iTunes version is installed on your computer. You can download the latest version here.

Connect the iOS device using the USB port on your computer.

Make sure that the computer is connected to the Internet and that Internet access is not blocked by firewall or security software.

Synchronise user content and perform a device backup in iTunes before restoring the device.

Please use these resources to ensure to avoid loss of data when restoring an iOS device:

iOS: Synchronising with iTunes

iTunes: backing up, updating and restoring iPhone, iPad or iPod touch software

iPhone and iPod touch: Backup information

iPhone: Improving backup and restore time by reducing the film roll on the iPhone

iPad: Backup information

iTunes: Alert "Backup could not be saved on computer"