Now, you know they're out there, those malicious people whose goal it is to steal your information right off of your computer! Let's talk about viruses first, seeing as it's typically very easy to get one, and some people don't know much about them. There are a few main types that I'll tell you about right now;
Trojan: a program that tries to damage your computer from within
Backdoor Trojan: a program used by a hacker to take over your computer. (AKA, he can do whatever he wants with it)
Keylogger: Basically, a keylogger can see everything you type. Including passwords, credit card numbers, and anything else.
Also, there are cookie grabbers, though not usually a virus, they can still steal your information. Basically, when you log onto any site on the internet, your computer saves a cookie for that login. Everytime you log into a website, your computer temporarily saves your login information, and deletes it when you log out. It's true that you can delete your cookies on most browsers, but that logs you out of every website you're currently logged into. And then, after you log back in, *POOF* theres some new cookies for ya. Cookie grabbers are a script, that can steal your cookies and give them to some sort of hacker.
When I first learned about all of that, it sounded pretty scary. But there are some things you can do to help.
First off, let's talk about internet browsers. If you're trying to keep your computer as safe as possible, it's best not to use Internet Explorer. I know, a lot of people love IE, but really, it doesn't have as many security options as most of the other browsers. One browser I would recommend is using Firefox. FF has several add-ons you can install to add security to your computer. I'll only go into detail about the one I have used.
One of them is NoScript. It pretty much takes blocks all scripts, until you click to allow sites, they're blocked. This program can be very annoying at first, but you are in good shape if a cookie grabber tries to get you. To download NoScript, click on tools > add ons > get add ons and type in either NoScript or script or something.
Now, I have several browsers on my computer, in case something should happen to one of them. I normally use Google Chrome, my backup is Firefox, and if desperate, I'll use Safari.
Also, please, PLEASE make sure you get some sort of anti-virus or spyware removal program. They are extremely important to keeping your computer safe! Now, I understand that they can be pretty expensive. I know of some free ones, however. :)
Avast Free Antivirus- This is obviously an anti-virus program, but I don't know much about this one in particular, I have been told by friends that it's a good program however. :)
Spybot- Spybot is some spyware removal that you can use, and it basically does a pretty thourough search through your computer for anything that shoudn't be there.
AdAware- This is probably one of the best free programs out there. It is a malware/spyware removal program, and it's faster than most combination programs. I would definitely suggest you download this!
Now, personally, I use McAfee. It works well for me, but then again, I didn't have to pay for it. My dad did. :P
Update On Feb 24, 2010: Just noticed I spelled the title wrong. D'oh!
Also, I somehow forgot to mention MalwareBytes. Not sure how I forgot that one, seeing as I have it on my computer as a second opinion... anyway, it's a good program. I usually run quick scans whenever possible, and full scans once a week or so. I find it's better to run full scans right before I go to bed, or before I leave for school. This program is great. :)