Download from the link below the files you need to replace notepad.exe with the famous notepad2 on your 64-bit Windows 7 machine.
Before you replace the old windows notepad.exe
Make sure you turn off the windows notifications in windows 7.
You can read this post for detail instructions.on how to configure UAC in Windows 7. You need to drag the slider all the way down to Never Notify.
Right click on replace.bat and select "Run as administrator".
That should do it!
The zip file contains all the steps specify in this post