Can I upgrade my unlocked iPhone 3gs from 3.1.3 to 4.0?

[VinhFTW]

I'm currently running my 3gs on t mobile and I want to upgrade to 4.0 just for the folders and ability to multitask.

I've heard that running an unlocked iPhone on 4.1 or 4.2 drains your battery that's why I prefer 4.0

I'm not to techy and need any advice I can. My modem firmware is 05.12.01 and model is mb716ll. I don't know what that means but I hope it helps.

[iYeow]

On the front page of cydia, if you see 4.0 shsh , then you either use tiny umbrella to help you verify your 4.0 shsh blob or point your hosts file towards cydia and you can just put your iphone into recovery mode and restore to stock 4.0.
Jailbreak it with Jailbreakme.com from Safari on your iphone.
Unlock with Ultrasn0w again.

[VinhFTW]

Is it easy enough to do myself? Or should I pay someone that's experienced to do it? I've never jail broken an iPhone or even seen anyone do it

[iYeow]

You need some basic knowledge about jailbreaking. If you don't feel comfortable, the consult a friend who knows about jailbreaking.