My 3G has 3.1.2 jailbroken with baseband 5.11 unlocked and hacktivated. My home computer runs Windows. I live abroad and do not have access to an AT&T SIM. I've read through many guides but I still haven't understood exactly what I need to do to upgrade to iOS 4 (presumably 4.2 but if an earlier version will give me less grief that may do). Do I need to upgrade my BB? Why or why not?