1. Start button, click on Run... and type "regedit" (without the quotes)
2. Navigate to
"HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileEx
ts"
3. Find the extension you wish to edit and click on the "+"-sign to locate
the key that says "OpenWithList"
4. In the right pane of the registry editor you'll see a list of programs,
like "paint.exe" or "notepad.exe"
5. Simply click on the one you wish to delete and press the delete button on
your keyboard
Note you can save the registry key first by:
On the File menu, click Export.
In the File name box, type SaveKey, and then click Save.
Or create a system restore point prior to editing.
Note: If the registry key is not there, you can simply create one by going
edit > new.
http://support.microsoft.com/default.aspx?scid=kb;EN-US;322756
HOW TO: Back Up, Edit, and Restore the Registry in Windows XP
Disclaimer: Modifying the registry can cause serious problems that may
require you to reinstall your operating system. Use the information provided
at your own risk.
