symantec corporate antivirus removal & Sophos install

Problem:
Tried to install Sophos after removal of Symantec antivirus thru control panel on a Dell Dimension desktop but no luck. In fact the home edition XP became unstable and would shut down by itself. Apparently Symantec Corporate version buries itself deep and doesn't de-install easily

Solution:
- backup HD on desktop with USB to IDE cable adapter
- boot in safe mode and cleanup registry using tips at
 http://www.ehow.com/how_4855666_remove-norton-antivirus-corporate-edition.html
- search HD for any Symantec files and delete
- search registry for any Symantec keys and delete all
- install Sophos