Before you update, you might want to consider preserving the BaseBand. The latest iOS 5 BaseBand can't be unlocked. Your iPhone will be worth $100 more if you preserve the BaseBand. To preserve the BaseBand, download Sn0wbreeze and the iOS 5.0.1 ipsw file. Open Sn0wbreeze and use BaseBand Preservation Mode. Sn0wbreeze will create a custom ipsw on your desktop. Connect you iPhone to your computer, open iTunes, hold down the shift key and then select the option that says Restore. It will let you select your custom ipsw that is on your desktop.