I have an Iphone 3gs currently running 3.1.2. Baseband 05.11.07 I did my original jailbreak and unlock using Blackra1n. I've been wanting to upgrade for a while but I've been afraid to lose my jailbreak and my unlock since I'm using T-Mobile and messing up my unlock would mean I would lose all my phone service. What steps should I take to ensure that I can restore in the event that I have a problem? What program/procedure would I use for this phone? I know that a few programs are Mac only. I'm running a PC with Windows 7 if that matters.