Hi intersec, dickevans and jbwnor.
Thanks for your replies and suggested answers which seem to fit with the timetable for my change to a later Norton version. With XP set to end next April I have just renewed my machine for one with Windows 7 installed and am now grappling with a whole lot of new problems. Haven't yet looked at details for Defrag but am comforted by your comments.
Regards Maqrnhullman.