Jailbreaking and unlocking iphone 2g/3g os 3.1(windows)

1. Download the 3.1 custom firmware(2g/3g) (password is "coderetard" for 2g custom firmware/3g custom firmware link is a torrent file).
2. Upgrade your iTunes to the latest 9.0 version.
3. Turn your iPhone off.
4. Bring it into DFU mode. To do so, while your iPhone is switched off hold the home button and connect it to the pc. Let go of the home button as soon as you see a data cable with the iTunes logo.
   
5. iTunes will automatically launch and ask if you want to restore the iPhone.
6. Shift click or option click on the "restore" button and find the custom firmware downloaded in step 1.
7. Sit back and enjoy the show on your iPhone.

Note:If you get error 1600, your iPhone is not in DFU mode