Help with JB

[madhavpatel6]

I currently have a iphone 3gs running
3.1.3 (7e18)
Carrier : AT&T 5.6
MODEL mc135LL
Modem Firmware: 05.12.01

I was thinking of upgrading to 4.0.1 but i dont know what to do...i heard that if you jailbreak on 4.0.1, you will not be able to upgrade your iphone...

Can anyone help and give me details about what whould happen and tell me if i should upgrade or stay on the same Firmware

[iYeow]

If you don't jailbreak, any new fimware release , you can just hit upgrade and everything will be intact.
When you jailbreak an iphone and you want to go to the next level, you have to do a restore which wipes out everything , even the jailbreak.
It is your choice, you do not need to jailbreak if have no use for it.