I've just had to do that for Norton System Works 2004 (running under Windows ME). Symantec's support site has a pretty good blow by blow account of how to remove their products manually. There is a little more to it than casually removing bits from the Registry. Go to
this bit for the full SP or do a search for Document ID:2001090708472107 - Removing Norton SystemWorks™ 2002 or 2003 from Windows 98/Me after Add/Remove Programs does not work
allow yourself an uninterrupted hour!