Thankyou, that was interesting, and thankyou for the PC security center web site address. I am still hoping for more advice in answer to my question for Windows operating systems other than Windows NT eg. Windows 98 or XP.
Incidentally, I am basing my understanding on these Symantec web pages:

Removing a virus from your computer when Norton AntiVirus is not yet installed
http://service1.symantec.com/SUPPORT/nav.nsf/pfdocs/2000012015322806?Open

and

Removing a virus using a Rescue Disk set

http://service1.symantec.com/SUPPORT/nav.nsf/docid/2001053109413806?Open&src=&docid=2000012015322806&nsf=nav.nsf&view=pfdocs&dtype=&prod=&ver=&osv=&osv_lvl=

Document ID:2001053109413806
Last Modified:02/11/2004

 Thanks, Mike