Thank you for your advice EFCLee1, I wasn't aware that there was a free version available, I have been running a free trial version for about a month and the trial period is about to expire in two days. So I am now getting messages asking if I would like to update/upgrade to avast internet security for £20, this has a silent firewall (what ever that is?).
That is what prompted the question, but if I can download a free version I will, is it the Antivirus6.0?
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Addition info;
I have just noticed that it is an upgrade from what I have(that is to be paid for) and the trial period was pre registration, all I need to do is register and I can continue with the existing protection, costing nothing.
So done that, didn't noitice it before, I am a bl00dy idiot!