My kids have been on loads of sites while ive been away and not one virus or malware has got on my PC

I run AVG 7 and Spybot search and destroy and Ad-aware but I also have found something that helps called Spyware blaster 3.4 found here http://www.javacoolsoftware.com/
this works also with Mozilla FF and fixed the javascript problem I had with IE that made me go to Firefox in the first place. All these programmes are FREE and Work for me .Does anyone know of any other good totally free protection tools?