Why Use Anti-Virus Software?
Bob Henry
It is critical that you install anti-virus software and keep it updated. Browsing the Internet, sharing files, infected thumb drives, portable hard drives, mp3 players, smart phones, etc. can all infect your computer with viruses. No computer is immune--Windows, Mac, Linux, PDP-11--can all be infected.
Many viruses don't do anything you would readily notice. They just run in the background using your computer to send SPAM or spread malware to the people you communicate with so that their computers send SPAM or infect other computers. All you may notice is that your computer is running more slowly or the drive access light is blinking all the time.
Anti-virus software does more than just protect from viruses. There is a lot of other bad stuff out there like malware that collects your keystrokes and sends them to a computer somewhere. Then the criminal behind the malware will try to use your information to steal your identity (think about all the usernames and passwords that you type and what you access).
If your computer gets a virus, you will probably lose some of your work and a technician will have to eradicate the virus from your computer--that usually means fully erasing the hard drive and reinstalling all your software. While that is being done, you won't be using your computer. Further, your infected computer probably passed a virus onto someone else's computer and that person will have go through the same process to disinfect that computer. It would be inconvenient to you if your computer got a virus, it would be irresponsible if you allowed one to be passed to people you communicate with!
For more information, check out this site, http://www.us-cert.gov/ncas/tips/ST04-005