I used Avast!, Antivir, AVG -FREE, and Norton.- SUBSCRIB.
Norton, I didn't feel like paying every year and didn't need that much security it offered for its bloatware. I just basically use internet, email, music, online games, limewire, yahoo!music, etc. So I just need basic protection.
AVG- I think its the oldest and less resource user but has the worst detections(not saying its bad) of the other 2 freewares.
AntiVir- The best of the freeware virus detections and scanning speed of the 3. It also has a pop-up ad everytime you turn you start your computer.
AVAST!- My pick, for it having the most features- autoupdate without popup but by speech of sound, nice interface, email scan etc.
Second best detection of the 3. BUT it is the longest scanning speed of the 3, for me a thorough scan would take 2.5 hrs for 25GB of used Hard disk.
I think that is the only problem-->long scanning.
But I wouldn't care, I'd run games at the same time or w/e while it scans.
http://www.pcworld.com/article/id,124475/article.html
For firewall I use Windows Firewall, and Linksys WRT300-N - SPI Firewall