If you have put off using anti-virus because you don't want to pay for it, there are several free and very good anti-virus programs available -- see the links to the right.
3. Create secure, original passwords. Creating unique passwords is one of the easiest ways for consumers to ensure their privacy and security online. See our password primer for tips.
4. Update your computer(s) with the latest vendor security patches. Fully 95 percent of all network intrusions can be avoided by keeping computer systems updated with the latest vendor patches, according to the CERT Coordination Center's Software Engineering Group, a government-funded computer security watchdog group at Carnegie Mellon University.
Visit www.uscert.gov for a comprehensive list of security alerts and vendor patches. Windows users can go to windowsupdate.microsoft.com to install the latest updates. Using Microsoft's automatic update notification service, users can get updates when they are released. Windows XP users can configure updates to install automatically.
If you don't know how to enable automatic updates from Microsoft, visit the company's tutorial.
5. Practice basic e-mail and downloading "street smarts." Most viruses are transmitted as e-mail attachments. Some may come from people you know; others will enter your inbox bearing enticing subject lines. Either way, users should be wary of opening all attachments, and scan each one with antivirus software before opening them.
Avoid opening e-mail attachments that contain ".vbs," ".scr," ".exe," or ".pif" file extensions. Files that end in these extensions are most likely to contain some sort of virus.
Also, it's a good idea to avoid clicking on Web links in e-mails if you are unsure of their origin. Plenty of bad things transmit themselves just by convincing users to visit malicious Web sites.
People who use "peer-to-peer" file-sharing networks such as Kazaa, eDonkey, and Bittorrent place themselves at a particularly high risk, especially when downloading "executable" programs, experts say.
Such nasties include "Trojan horse" programs that allow attackers to control your computer from afar, and keystroke loggers, which can record everything you type on your keyboard, including passwords and bank account numbers.