Get Anti-Virus Software: Up-to-date anti-virus software is the first defense against viruses for people running non-secure operating systems (all but UNIX or Windows NT). Companies that sell these products, such as Symantec and McAfee, provide frequent updates to combat the latest pests. Update Your OS: Just as anti-virus software adapts to the latest threats, your operating system will also need updating as bugs and vulnerabilities are identified by programmers. These are usually called updates or "patches." People using a version of Microsoft Windows can get the latest updates at http://www.windowsupdate.com. Avoid Attachments: Viruses are often delivered through e-mail attachments that are executable files. Don't open attachments - even from people you know - unless you've specifically requested the information or verified the contents from the sender. Be especially wary of files with the extensions ".exe," ".com" and ".vbs." Install A Firewall: They are common on larger networks, but home users should also consider installing a firewall, which acts like a security gate in controlling traffic to and from your computer. A firewall takes some commitment on the users' part in configuring the rules and exceptions as to how it will operate, but the payoff can be significant in terms of security. According to CBS News Computer Consultant Larry Magid, ZoneAlarm offers an excellent free program for personal use. Back Up Your Files: If you do fall victim to a malicious attack, or if your computer is somehow destroyed, don't lose all of your data. Take some time to identify important files on your computer and make copies of them on a routine basis, taking into account how often they change. Download With Caution: Be wary of downloading programs or files over the Internet, or from CD-ROMs received in the mail. It's important to learn as much as possible about the person who made the software, and what it is supposed to do, in these situations. Buying products on CD-ROM from reputable retailers all but eliminates the threat of an attack in this manner. Perfect Your Passwords: Yes, it's nice to have passwords that you're able to remember, but not if they nullify the purpose of having them in the first place. Passwords should be tricky for someone else to figure out, and should not be written down. The experts at the Carnegie Mellon Software Research Institute suggest each password should be: as strong (length, content) as allowed; unique from your other passwords and also from standard words you'd find in the dictionary; practical enough so you don't have to write it down to remember it; something you change on a regular basis. Sources: Carnegie Mellon University/CERT, PCAnswer.com, Howstuffworks.com