OK...

I have worked in Windows Support for over 11 years and I would avoid all the applications that The Architect mentioned, you can't trust a piece of software that gets reported by another piece of software for the offence it is trying to protect you from... AVOID

I would recommend these for free and they are just like Ronseal products (does exactly what it says on the tin).

Anti-Virus -: AVG
Firewall -: Zone Alarm

I have used both these products myself in the past and both do a superb job for free.. Both are easy to use and easy to setup and maintain. Oh and always download software from the manufacturers sites only, never via sotpedia or other sharing sites as you do not know who has done what with it.

The reason I say that is I am now a Web Developer and have discovered very quickly that the internet if full of cowboys and conmen waiting to take advantage of users who fail to read information and then fill your PC with crap.

Enjoy.