The whole thing with the internet is that it's - relatively speaking - free. That is to say, you pay a monthly fee too your internet service provider. And you pay for your computer. But once you're online, access to the content that is produced anywhere in the world doesn't cost you a penny you don't want to spend. The information superhighway has no toll booths.
And part of that lack of regulation is that you run the risk of ending up with a virus or two on your computron. This is just part of the metaphorical price you pay for access to the information, and it's a price that is typical of any medium in which knowledge equals power.
Think about it: very few people are law experts except for lawyers. The lawyers then use their mastery of the law to either extract money from you directly, or to rearrange inttterpretation of the law in order to favor them. And, of course, lawyers are there also to protect you from other folks who are willing to break laws in order to take advantage of you.
The internet works the same way, except instead of lawyers, you have hackers, programmers and free anti virus programs. Hackers are the ones with both the knowledge and anonymity to invade your computer and steal whatever information - credit card and bank account numbers, user history, whatever - they can get their hands on. Programmers are the equivalent of civil rights lawyers trying to protect the innocent from those who would flaunt the law. And free anti virus programs are the cops.
Ok, maybe I stretched the metaphor a bit, but the point I'm making is that, if you're running your computer without anti-virus protection, you're exposing yourself to intrusion unnecessarily. And unless you're part of the 1% of folks who can thoroughly examine and de-bug their computer with no outside, expert help, then you should take this warning seriously:
You need free anti virus programs. You need this to protect your information. Because if you don't have them, then any hacker on the web can implant a virus on your computer and turn it into a zombie spambot, or steal your information, or use your computer for god knows what. It's something you have to be cognizant of, because, like any other aspect of life, if you don't protect yourself, you will be taken advantage of. It's not a matter of "if." It's a matter of "when."