Hey. I find this is worth doing to stop itunes from upgrading your phone or accidentally upgrading.. (if you set a jailbreak up for a friend who might not be wise to JB's... worth doing this to them!) Download FWChanger from Cydia and set custom firmware, then reboot i set mine to 3.1.3 and i used build 7E18. For those who dont know what this prog does, basically it just changes the number of your firmware, and nothing else (as far as i know), so itunes picks it up as your running latest firmware (when really you are not!) Now itunes says my software is up to date!