Here are some of the free utilities that I use.
AntiVirus.
I have used Avast Home antivirus software for several months. I have found this to be an excellent product and would recommend it. It is free for home use, you just have to register it every year for free.
Firewall.
I used to use the old version of Kerio Personal Firewall, but a couple of months ago, I found Comodo Firewall Pro . This is a free for life firewall that is regularly updated.
Spyware removal.
For spyware removal, I have used Lavasoft’s Ad-Aware SE Personal. This again is available free for home use.
Posts 
Avast is one of the very few really antivirus programs that offer real-time protection for home PC security. Czech guys did a great job! AVG and Avira seem to be the only competitors. Finding a full-featured free antivirus is tough these days, most of the so-called “free†programs are either time-limited trials, or simply on-demand scanners without real-time monitoring. To my mind, avast! has the best interface of all free AV’s available for personal PC security.