I would like to update my iPhone 3gs. It’s on firmware 3.1.3 and I would like to update it to the latest firmware or to 4.1. How can I update with or without losing the jailbreak? I would like to know if there is any software or program that I have to install to make update possible. What can I do for software update of iPhone 3G 3.1.3? I would really appreciate your useful information regarding this. I hope to hear at the earliest from you guys out there. Thanks.