for spyware. If it finds any, it notifies you immediately and allows you to delete the file. You must also keep your antispyware software up-to-date because new spyware threats are discovered regularly. Plenty of high-quality antispyware tools are available free of charge, although many antivirus suites (which usually cost money) include them nowadays. Recommendations: Ad-Aware is freely available from Lavasoft (http://www.lavasoftusa.com/software/adaware), and Spybot-Search & Destroy is freely available from http://www.safer-networking.org/en/download. Firewall: A firewall monitors inbound and outbound Internet connections on your computer - that is to say, it checks when your computer tries to connect to the Internet, and when other computers try to connect to yours. The newest versions of Windows, XP and Vista, come with a built-in firewall that is on by default, so you don't have to do anything. Recommendation: If you have an older version, I recommend ZoneAlarm, available from http://www.zonelabs.com. Additionally, you should install new security patches for your computer as soon as they're available. See http://microsoft.com/security for more information about the Windows patching process, or http://www.apple.com/support/downloads for the latest Macintosh security patches.             Staying Up-to-Date Perhaps the most important fact to remember about your security online is that it's a never-ending battle. Phishers are devising new tricks on the hour, and new strains of computer viruses and spyware appear daily. In addition to keeping your software tools up-to-date, it's critical that you keep yourself up-to-date with new developments in the world of security so you know what kinds of new scams to look out for. Updating Firefox You need to keep your antivirus and antispyware software current. However, it's also important that you keep your version of Firefox up-to-date as well, because the Mozilla Foundation will release security patches from time to time. Firefox automatically checks for updates once a day. If any are available, it downloads and installs them and notifies you upon completion, providing that the update is compatible with your extensions and themes. Virtually all critical updates (such as those that fix security flaws) are compatible, but major Firefox updates (such as from version 1.5 to 2.0) might be incompatible. If you're using an extension or theme that is incompatible with the updated version, Firefox presents a list of the incompatible extensions and themes and asks you to confirm the update. Click the Show List button to see the list of incompatibilities. If you proceed with the update, Firefox automatically disables the incompatible extensions and themes until their authors release compatible versions. When compatible versions are released, Firefox discovers and installs them the next time it checks for updates, and then Firefox re-enables the extension or theme. That's because the update feature checks for updates not just to Firefox itself, but also to your installed extensions, themes, and Search Box engines. If you don't like the automatic update features, you can disable them and check for updates manually. Even if you leave automatic updating on, you can still check for updates manually at any time. I discuss these options in the following two sections. Disabling automatic update checking or installation