PLEASE READ: The 4th and 5th digits of your serial number is the week the iPhone was manufactured. If your phone is week 45 (Nov 9th 2007) or newer AND you've "accidentally" upgraded to firmware 1.1.3 in iTunes you CANNOT Jailbreak/Unlock your iPhone at this time. PLEASE PROVE ME WRONG.
FOR THE REST OF US:
iClarified has the best installer for upgrading to 1.1.3.
hxxp://www.jailbreak113.com
or
hxxp://www.iclarified.com/entry/index.php?enid=611
- The official dev team installer caused my sound to disappear