A worm is a form of malicious software that makes copies of itself.
A virus is a program or malicious code that secretly replicates itself by attaching to a medium such as another program, the boot sector, a partition sector, or a document.
Unlike a virus or worm, a Trojan horse does not replicate nor make copies of itself. The main purpose of a Trojan horse is to compromise security such as stealing passwords.
Antivirus software should be installed on all computers. Keeping the signature files up to date is also important.
One of the most common ways that viruses are spread is through email attachments.
Critical updates are those updates that are deemed important to the normal functioning of a computer.
Windows XP supports Automatic Updates. This feature can keep a computer up to date with the latest critical updates with little user intervention.
Microsoft Security Baseline Analyzer (MSBA) is available from the Microsoft Web site. It can tell you which updates are missing as well as any configuration changes that you should make to increase security.
