Liam, once again thanks for your help. Your instructions left the machine much more stable, I then ran AVG, AdAware and SpyBot again. Both AVG and Spybot removed yet more items! I reloaded Norton Internet Security and this time it managed to complete its live update. Norton found TFTP2740 W32.Spybot.worm and deleted it.
The machine now seems clean and I have also found a directory with what appears to be service packs 1 and 2, I will give those a go and then hand the machine back to its owner - apparently he recently bought it second hand and has only used it on the Internet for less than an hour.
Thanks again
TeeS