I respect Ians valuable advice but I 1: have heard of Sophos in the past, so I am going to run the two of them (ClamXav&Sophos) - I have a backup just in case, but I do not think that there will be any problems.
I DO like to experiment with my favourite MBP.

It's how we all learn, and it doesn't cost a penny.
I'll be letting everyone know how it goes, good or bad.
Thank you to the OP for the info & link, and thanks to everyone else for your valuable, trusted opinions.