Instructions for Jailbreaking your iPhone 3G ONLY on Windows (tested on Vista, but should work the same on XP)
MAKE SURE YOU HAVE A BACKUP OF YOUR PHONE
1. You need to download two files:
x12220000_4_Recovery.ipsw and iPhone1,2_2.0_5A347_Custom_Restore.ipsw. You can get both of them over here:
2. Make sure you have itunes 7.7 installed.
for vista: Click start then copy this into the search box and press enter after:
for XP: click start then run, then copy this into the run box:
3. Make a directory callled: Device Support
If it already exists, clear it.
4. copy x12220000_4_Recovery.ipsw into the Device Support folder you just created.
5. ok, you need to get your device into DFU mode. watch this video to see how:
6. Once your phone is in DFU mode and detected by iTunes (should be black screen on phone NOT itunes logo with usb cable), click on iphone in itunes, then hold the SHIFT key and click on restore.
7. Browse to the folder where you downloaded iPhone1,2_2.0_5A347_Custom_Restore.ipsw and select it. itunes will then extract the file and you will see the ipod dev team's pinapple logo pop up after a few seonds, like this:
8. when restoring has completed, it will ask you to connect to itunes, then re-do the activation process (download carrier settings)
9. Restore your backup! this should automatically be made. it should pop up right after downloading carrier settings, but you may also do it by right clicking your iphone on the left, and selecting "restore iphone"
10. That's it, you're done!
Disclaimer: I am not responsible if any of this bricks your phone. i have tried it myself and with another OCAU member and it has been fine, but THIS IS AT YOUR OWN RISK