Right mate i have just done this .
you need a program called quickpwnrc3 pm me and ill send
go to this
THIS website and download the following firmware named
iPhone 2.0.2 ipsw Download (241.84MB - 86,231 downloads)
right once you have done that you need to open quickpwnrc3
plug you phone in turned on!
select from the program which iphone you have ie for you it will be iphone.
select it and click the arrow for next
click browse and find the firmware you just downloaded.
let it scan it and when its done it will put a green tick , click the next button.
follow the onscreen insturctions to get into dfu mode. then asoon as you iphone screen goes white unplug the usb!!
then do the shift and restore in intunes and you shouldnt get a error massage if it u get 10** or a 20 error then its not in dfu mode so repeat the above..
go back into quickpwnrc3 and you iphone screen will still be white, run the program again and it will jailbreak to 2.0.2
but if you want the standard oe firmware then you dont need to jailbreak.