Freeware Security Tools
For consumer users, there is a great variety of freeware computer security tools available. Most of these tools will try to upsell you to a paid for "pro" version of their software, but the free versions are really quite nice. Most of these tools are also aimed at the Microsoft Windows environment because that is where most of the security problems occur.
AVG Antivirus (found at free.avg.com) does a fine job of keeping your machine free of viruses without using too many of your computer's resources. Definitions update automatically each day and, for consumers, there is no definition subscription to run out of or have to pay for.
Avast! antivirus also has a free program for consumers. The current version of Avast! seems to be lighter than the current version of AVG. The free version of their program can be found at the Avast! website.
Microsoft Security Essentials (added 5/25/2010) is a new entrant into the no-cost antispyware and antivirus market. There is no cost to download, install, or run the software although a validated copy of Windows XP, Vista, or 7 is required. A nice summary of the software can be found on the Register's site.
Spybot Search and Destroy is a very good anti-spyware tool. This software does a good job of removing bad programs that are not viruses from your machine if it is updated and run regularly. One caveat to this software is that when it is installed, the tea timer realtime protection should be unchecked and not included. The real time protection for spybot does a fine job, but it costs a great deal of machine resources to run. You are better off running a scan from time to time as opposed to using the real time protection. Spybot does not support automatic signature updates, but the process for doing the manual updates is straightforward and easy to do.
Lavasoft Adaware compliments Spybot nicely. Lavasoft gives away a free version of their program, but also tries to upsell you to their Adaware Plus software. The free version is just fine and I recommend using it in conjunction with Spybot.
MalwareBytes is a relatively new entry into the anti-spyware space - at least one that I've recently found. It does a good job of removing pesky infections and does have the advantage of installing and updating when the machine is running in "safe mode with networking."
SpywareBlaster is another nice utility. This one does not scan for and remove spyware. Instead it downloads a database of "known bad URL's." This will prevent both FireFox and Internet Explorer from visiting those sites that will force a download of spyware onto your computer. This is a very useful tool. The difference between the free and the pro versions is that the pro version allows for auto-updates of the database.
Microsoft Security Essentials (added 9/30/2009) is a new entrant into the no-cost antispyware and antivirus market. There is no cost to download, install, or run the software although a validated copy of Windows XP, Vista, or 7 is required. A nice summary of the software can be found on the Register's site.
The browser you use to access the web can also make a difference on whether or not you catch spyware or viruses on your machine.
FireFox - FireFox is a free, open source web browser that is available for Windows, Mac OS, and Linux. The browser itself is designed to be more secure than Internet Explorer and doesn't hook nearly as deeply into the operating system as Internet Explorer. It also has a modular "add-on" system that allows the addition of many very useful helper programs.
AdBlock Plus helps FireFox by preventing the download of advertising content unless it is allowed by the user.
What you can use depends a lot upon which e-mail client you have.
Microsoft Outlook - The full version of Outlook 2003 and 2007 have built in junk mail filters that work a little bit. The largest issue with the Outlook junk mail filters is that they don't have a good way of being trained about what you would consider spam. I would recommend an open source program call spambayes to either take the place of or work in conjunction with the Outlook junk mail filter. Spambayes uses a statistical engine to recognize junk mail versus good mail and works amazingly well after it has been trained a bit. Their website claims that the software also works with Outlook Express and Thunderbird.
Mozilla Thunderbird - Like Outlook, Thunderbird does have a built in junk mail filter, but their filter is trainable. There are also some aftermarket add ons that improve the filters performance. Spamato is an open source filter set that works with Thunderbird (and Outlook) - in addition to the statistical filtering of SpamBayes, it uses other methods of classification to catch spam.