All the security installed on my PC is freeware

Sygate Personal Firewallhttp://smb.sygate.com/products/spf_standard.htm
AVG free edition anti virus (http://www.grisoft.com
Spybot S&D http://security.kolla.de
Adaware SE Personal http://www.lavasoftusa.com/support/download/#free
SpywareBlasterhttp://www.javacoolsoftware.com/spywareblaster.html
Spywareguardhttp://www.javacoolsoftware.com/spywareguard.html
Once downloaded search for Updates

I also recommend
Regscrubxp (for win xp users)Registry cleanerhttp://www.majorgeeks.com/download.php?det=2048
CrapCleaner http://ccleaner.com// for Win all