Anti-virus: What do you actually look into?

I've browsed through the Security questions, and found quite a lot of people asking about recommendations about anti-virus softwares. What I find is some people do not really know what really suits them for anti-virus softwares.

Thus the question I'm asking in the title above. When choosing anti-viruses, what do you actually consider about? Is it that you like free anti-viruses? Or are you looking into the ones that are user-friendly? Do your type of anti-virus software be light on resources, or would you prefer superior protection?

Discuss about it here. You can use the current product you're using to support your reasons.

Anti-virus: What do you actually look into?antivirus scan

I use Nod32. It seems to be light on resources and I believe has a perfect virus catching record.

For free software I like AVG free. It is also fairly light on resources and user friendly. I recommend both to people when Norton has bogged down their system to a crawl..

Anti-virus: What do you actually look into?computer security

I don't use any anti-virus software. I have a hardware firewall that keeps unwanted ports closed to prevent any outside access and I am the only one who uses my computers, I have enough experience to know what to download and what to stay away from. My experience in working with other's computers has given me the resources to eradicate any viruses I would come across, but in 10 years I haven't had any trouble. I don't like the drag on the resources, paying when I don't need to, and seeing alerts pop up all the time.
I'm sure that most people have security in mind when thinking of things like antivirus software. Cost can be an issue, but there's plenty of decent software out there. I can think of Avast and nod32 as good choices.