How I changed my IE default ‘View Source’ editor from Notepad to TextPad.

1) Open Regedit by typing ‘regedit’ (sans quotes) in the RUN (XP) or Start Search (Vista) dialog box. (winkey+R will bring up the RUN dialog in either OS).

2) Navigate to the following location:
HKEY_LOCAL_MACHINE
>> Software
>> >> Microsoft
>> >> >> Internet Explorer
>> >> >> >> View Source Editor (If this doesn’t exist then create the Key)
>> >> >> >> >> Editor Name (If this doesn’t exist then create the Key - under View Source Editor)

3) Set the (Default) value = “C:\Program Files\TextPad 4\TextPad.exe”
(or to the text editor of your choosing)

Now Internet Explorer will use your preferred editor. I believe you will have to close IE if it is open for this change to take effect.

ENJOY!