Links down here to Downlaod Orignal Firmware for Iphone ( OS 4.1)
click on these links and save the file on your pc
How to restore or update your iPod/iPhone/iPad:
After downloading the desired firmware below, you can shift-click (PC) or option-click (Mac) the Restore or Update buttons in iTunes. A file dialog will open and let you choose the downloaded ipsw-file.
Note: Your browser may change the ipsw-file into a zip-file. In that case, just rename it