Knowing what viruses are and what they can do will help you avoid them.

Computer viruses are not living creatures. They are malicious computer programs that 'infect' your computer. You can get a virus by running an infected program. Most viruses today come from the Internet, and e-mail attachments. Some computer viruses do little or no damage to your computer; others can destroy your important documents or send e-mails with a virus to all of your friends.

What to do if you think you have a computer virus
Don’t Panic. Make sure your virus software is up to date. Use your virus software to scan your computer for viruses. The software should be able to clean most viruses from your computer

How to Protect Your Computer

• Use virus protection software such as McAffee or Norton Anti-Virus. New viruses appear all the time, so download the updates to the software at minimum every month. Scan your computer for viruses regularly.
• You cannot get viruses from surfing the Internet, but you can get viruses by downloading programs and running them on your computer. Only download programs from places you trust.
• You cannot get viruses from reading emails, however attachments can contain viruses. Do not open attachments unless you are expecting them and know what they are. Even if one of your friends or family members sent you the file, be skeptical. Your friend's computer may be infected with a virus, and your friend may not realize. If you receive a file unsolicited from someone you don't know, delete it! Never open files ending in .vbs, .com, or .bat, and be very cautious with .exe files.
• Scan floppy disks you get from others; they could contain viruses as well.
• Avoid illegal and pirated software, as they often contain viruses.
• Don’t believe everything you read: People often forward email warnings about viruses. Most of those emails are hoaxes.

On-line resources:

Learn about different kinds of viruses, their origins, and more.
http://www.howstuffworks.com/virus.htm

Online edition of a virus encyclopedia
http://www.virusdatabase.com

A list of e-mail viruses and virus hoaxes
http://www.snopes.com/computer/virus/virus.htm