how to restore your iphone without upgrading the firmware

Here the instructions:
To restore your iphone without upgrading the firmware... follow these steps

you would need
1) the original firmware.ipsw
2) the most updated firmware.ipsw

To start -

1) run itunes, and plug in your iphone
2) open itune working directory,
C:\Documents and Settings\*****\Application Data\Apple Computer\iTunes\iPhone Software Updates
3) if you have downloaded the software updates for your iphone, it should appear in this directory
4) put your iphone in recovery mode (power+home 25sec)
5) itunes will need to restore your phone, click restore
6) itunes will ask to check the internet for updates, click Check
SKIP To 8 if you have already downloaded the updated firmware
7) wait for download to finish (donot click restore and update yet!)
HERE the simple trick (if itunes starts to unpack already..then uve done it wrong..click cancel)
8) rename your the original firmware.ipsw to same name as the updated firmware.ipsw
9) copy your renmaed original firmware to the C:\Documents and Settings\*****\Application Data\Apple Computer\iTunes\iPhone Software Updates overwriting the updated firmware
10) click restore and update and it should unpack the original firmware and reflash.