I have updated my Iphone firmware to 2.0 but i don't like it , so I am trying to downgrade it back to 1.1.4 now, but I got trouble when i was restoring

I follow the step in the following:
Before we begin please budget about 45mins of your time to get this done.

*This is only for 1st Generation iPhones that have been upgraded... not for 3G iPhones*

1. Download iTunes 7.5 from here: Direct Download iTunes 7.5 to Activate iPhone Anywhere Internationally My Digital Life
2. Uninstall your current version of iTunes and reboot your PC.
3. Go to My Documents > My Music > iTunes and delete the file called "iTunes Library.itl"
4. Install iTunes 7.5

Note for OSX users:
If you are on OSX and want to attempt to downgrade your iTunes, you can try these steps:

Load up Terminal and type the following:
killall iTunesHelper
sudo -s
rm -r /Applications/iTunes.app
rm -r /Library/Receipts/iTunesX.pkg
rm ~/Library/Preferences/com.apple.iTunes*
rm -r /Applications/iTunes.app
rm -r /Library/Receipts/iTunesX.pkg
rm ~/Library/Preferences/com.apple.iTunes*
rm -r /System/Library/PrivateFrameworks/MobileDevice.framework

5. Download the 1.1.4 restore file from the here http://www.modmyi.com/forums/dow...o=file&id=2231 if you don't already have it.
6. Put your phone into DFU mode using the following steps
a. Plug your phone into iTunes (ignore the message that pops up)
b. Power the phone OFF
c. Hold power and home for EXACTLY 10 seconds
d. Release power (continue to hold home)
e. iTunes will recognize iphone in restore mode
7. Hold shift and click Restore - select the 1.1.4 firmware file you downloaded
8. After it's done restoring you will get error 1015 and the phone should be in recovery mode (iTunes logo with cable)

everything works until step 8, when I restore it using the 1.1.4 i have downloaded . and just right after extracting software , this is an error saying that "The iPhone "iPhone" could not be restored. An unknown error occurred (20)."
I don't know what is going wrong since I follow all the steps that I should follow. I uninstalled itunes 1.7.7 and installed the older version 1.7.5 already. but i don know why it still wouldn't let me restore my iphone to firm 1.1.4. does anyone know how can I fix this problem... I have spent different kind of method for almost a day but i can't figure out the way to solve this problem... hope anyone can help me with this issue