Quoted from Thea Burger’s Blog
Want to change your default View Source editor from Notepad to say Notepad2?
Run REGEDIT, follow the following directions to the proper key.
HKEY_LOCAL_MACHINE
|- Software
|– Microsoft
|— Internet Explorer
|—- View Source Editor
|—– Editor Name (Default) = C:\windows\notepad.exe
If this doesnt exist (but it should) then create the Key “View Source Editor”.
Then create a Key within that named “Editor Name”. Modify the “(Default)” value to make it point towards any program on your computer using “D:\Tools\Notepad2\Notepad2.exe” (without the brackets).
[Open Tech Support]
