Thank you all for your replies. It has given me something to think about.
Although I am a little confused as to the adaware, malware programs etc as I had heard (again, this is going back 10 years ago) that these programs open up the machine to hackers and spyware.
Many of the programs I have seen listed in these replies, I have never heard of before, such as Avast, Avira, Hitman PRO, Kaspersky IS, Eest Smart Security, Sandbox/virtualization software...
I guess that is pretty much everything listed except for Nortons