I use and love AVG...
but to be honest, if your not downloading sketchy things, emails, ect. and you stay away from unsafe/unknown sites you really don't need one.
My old roommate never had any virus protection and his PC was just fine.
Ha. Yeah right. That's what you say. Antivirus is essential my friend. Especially if you go with a free one. Personally I used to use AVG, but now I like and recommend Avast.
I worked on one machine, maybe similar to arges86's friend's machine, an xp laptop, no antivirus ever installed in a few years from what I could tell. They just wanted a tuneup. No big deal. But I think I removed about 600 different things from that machine.
Seems to generally keep the system clean. Granted Windows does have built in firewall which is fine for most people, but nice thing on this one, you have to teach it. It seems decent at detecting if things are trying to go in or out of your pc to and from the web, and allows you to block or allow them. Using this combination, I've had relatively few issue*knock on wood*. But still stay away from unknown sites.
I use Avast, Avira and AVG on multiple machines. Avira seems to be the less intrusive in terms of slowing down performance, but that's just my observation. Yeah, I would never put a system into use without installing an updated AV of some nature. I also block all third party cookies and use IOBIT 360 on occasion to block/remove any additional suspect cookies/spyware. Be kind of difficult to maintain an important machine without the ability to run through all this software each day and kick out the trach.