The only ways to avoid getting a nasty program on your computer are to never get on the Internet and never load any programs on it.

Okay, that's not very practical. So what can you do to stay safe and still actually use your computer?

Think of your computer as a house. There is a front door, a back door, windows and a mail box that can all allow things to get in and out. Most of the time the sidewalk leading up to your front door is the main entry and exit point - this is your Internet connection. By using a Firewall program, you keep the front door locked so that someone passing by (a computer that is scanning the net for unsecured computers) doesn't get in if they try to turn the handle. It also keeps a lot of things from going out the door without your knowing about it.

You look through the windows to see what is outside - this is your Web Browser. It is usually safe to leave the windows open, but occasionally there will be a hole in the screen that lets bugs in. By staying current with Windows Updates, these holes are patched as soon as they are discovered. Left unpatched, these holes can get bigger and bigger and allow more nasty things inside.

Your mail box allows you to get letters from people - this is your e-mail program. You bring in the mail, and in addition to the note from Aunt Barbara about her latest trip to Barbados, there is a small box that says it has a gift for you inside. When you open the box, you see that it was just a cheap way to get you to open the box - it is not a gift, it is a mass of confetti that gets all over the place and makes a mess of things. Your AntiVirus Program would have alerted you before you opened the box, and kept the confetti from spreading all over.

You may think your back door is not used much. But occasionally a guest in your house might have a bunch of friends waiting outside, and they open the backdoor to let them in without your knowledge. File sharing programs like iMesh and KaZaA do just that by installing 'helper' programs that gather information about you and send that off to other computers.

Even if you don't use a file sharing program, you can get spyware on your computer simply by surfing the Net. A lot of these programs masquerade in ways that fool the firewall and antivirus program. Once they are there, they open the back door and invite others in to do what they wish. By using the back door, they can escape detection, but Spyware Removal programs can find them and get rid of them.

All of the programs mentioned here will help secure your computer, but you must use them and keep them updated. If you have a set of encyclopaedias from 1970, all of the information in them is still good, but you would not be able to look up information about Dolly the Sheep or hydrogen fuel cells for cars. Each of the programs has a list of things that it looks out for, but as new threats are developed the programs need to be able to address them. Like the old encyclopaedias they will be able to handle what they know, but they will quickly become outdated. Having an out-of-date program 'protecting' your computer is worse than not having it at all because it gives you a false sense of security.