Rendelmann's Home

Found this via [Don Park's Daily Habit], and checked: it also works for Windows 2000 -

How to replace Notepad.exe on Windows XP/2000

Windows XP/2000 has file protection so Notepad.exe will get restored if you just replace the file with renamed Sc1.exe. Follow these steps:

1. Download Sc1.exe from SourceForge or Notepad2 and rename it to Notepad.exe
2. Save a copy of the original Notepad.exe somewhere.
3. Replace Notepad.exe in following three locations (order is significant):
    
   • %WINDIR%\ServicePackFiles\i386 (if any SP is installed)
   • %WINDIR%\System32\DllCache
   • %WINDIR%\System32
   • %WINDIR%
     
     *%WINDIR% is your Windows folder (i.e. C:\Windows)
      
4. Press Cancel when a warning dialog appears.

That's it. Enjoy.

Update: have a look at simonguest's post how to get that work on Vista too.