2g iphone 2.1 messed up

i just recently got an iphone from my friend, the problem is it still has all the contacts,messages,apps and his settings... what i want to do is restore it back to scratch so its like a brand new phone and put only my stuff on there...

its an unlocked tmobile iphone 2.1 firmware 2g i think, its 8 gb silver and black plastic on the back...


so i followed this tutorial http://www.iphone-hacks.com/forums/about1773.html , but when i get to use quickpwn, where it says uploading exploit bootloader, it takes a long time, its been like 15 mins..... also as soon as it gets to this point, windows tells me the usb driver malfunctioned... now i cant use the phone cause its all locked up at the emergency screen saying i need a valid sim card and quickpwn isnt unlocking it...... what should i do?? however on the emergency screen it still says tmobile with bars next to it