My family and I have only been using ZoneAlarm. I think it's legit, if you know about computer then you know which processes to allow and which to block.
I use one just to be sure (AVG). I've never been infected, and I don't use blackhat tools whatsoever, but if you don't use them or download them then why not have an AV anyway? Lots of sneaky java-drive-bys out there. This should still be in computer section as it's discussion but I'll leave it here for now.
Every computer my family owns has at least one... I have a old one I'm messing around on I'm have alot on it.. Ya you can guess it that one is virus free ATM.
AVG is the shitiest AV ever made. It doesn't pick up anything. Norton is what I use. Im to cheap to buy the full version, so I just cracked it myself. It's just beast.