Glenn's free software for protecting your computer

A Discussion of SPAM, Viruses, and Social Engineering Attacks
that may be made against your computer
and what you can do about them.
Discussion document
Avast! 4 Home Edition

Protection from viruses that might try to infect your machine.
Here are some setup hints for Avast! 4 settings.

Note that using an email client other than MS Outlook Express and a browser other than MS Internet Explorer, and not opening unknown attachments is almost as good as having an anti-virus software.
Avast! Home page

Avast! 4 Home Download page

Avast! Home (re-)registration page
Anti-Virus Grisoft (AVG)

[Note: Avast! 4 seems to do a better job of automatic updates than AVG.]
[Another problem with AVG for mobile laptops is you have to tell it whether you get your email from a dialup or LAN connection. Avast allows either, dynamically. The setting can be found in the " AVG Control Center Email Scanner" Properties, then "Personal Email Scanner Setup" then click on the button for "Network Connection"]

Protection from viruses that might try to infect your machine.

Note that using an email client other than MS Outlook Express and a browser other than MS Internet Explorer, and not opening unknown attachments is almost as good as having an anti-virus software.
AVG Home page

AVG free edition download page

Other free anti-virus software
Zone Alarm Firewall

Protection from network attacks, and some trojans

An excellant firewall, fairly easy to configure and use, but not compatible with Windows' ICS. For machines running Windows' ICS feature, either buy Zone Alarm Pro, or Comodo

I've found one obscure bug with ZoneAlarm, Free edition (not known if it is in the other editions). You won't encounter this unless you run service programs on your machine that other applications are expected to connect to via well-known port numbers. Programs that run as services, and get launched before ZoneAlarm itself is fully activated, get their already-open ports ignored by ZoneAlarm when it starts. So even if the program has been approved to be a local and/or network server, all requests to it are blocked, because ZoneAlarm didn't open the port(s) for that program. The only workaround I've found so far is to be sure to launch the program after ZoneAlarm is fully activated... for a service program, this means setting the program to Manual start, and then starting it in a startup batch file or shortcut after ZoneAlarm is fully activated.

ZoneAlarm works well on XP, but with Windows 7 (I skipped Vista), it silently blocks incoming requests without even offering to open up the appropriate ports or approve the application. Whether this is a bug in ZoneAlarm or Windows 7 is indeterminable, but Windows 7 allows it (and maybe much too much more) when ZoneAlarm is not running.
Zone Labs home page

ZoneAlarm Free download page

ZoneAlarm Release History and Downloads page
ChoiceMail Anti-SPAM

If you use Google-hosted email ( or a private domain), then you already benefit from the easiest to use, effective anti-spam technology. If you can't use Google-hosted email for some reason, then ChoiceMail is the most effective anti-spam technology, and is also fairly easy to use.

The free version of ChoiceMail will protect one email account from SPAM. The paid version will protect more than one email account. Email from regular correspondents will come through without delay. Email from people with new email addresses, and from new correspondents, will get "stuck" in the "unknown senders" list. Those people will get a "challenge" message, and if they can figure out how to respond (it is easy, but not from all types of devices, like pocketmail) then they can register, and you will be alerted. You should manually check the "unknown senders" list occasionally, to see if any "real" messages are mixed in the junk. They stand out pretty well against lots of junk mail. And there is a "safe preview" mode so you can look at the associated email if you can't tell from the header than it is good or junk.

Most anti-SPAM products use blacklists (which are almost useless, as most SPAMmers change their spoofed From addresses with each batch of messages) or are based on Bayesian (statistical) filtering, augmented by manual classification of messages as SPAM. These work to a fair degree, but their percentage of mis-classifications (falsely classifying messages as SPAM that are not) is too high for my liking. Bayesian filtering is why SPAMmers seem to not be able to spell... maybe they can, and maybe they can't, but intentional mis-spellings bloat the statistical database, and reduce the likelihood that SPAM will be correctly classified.
Choicemail page
Free version is ChoiceMail One 3.x

Direct download link
Spybot Search and Destroy

Some "free" software, and even some purchased software, comes with embedded monitoring software, which theoretically only reports "anonymous" information back to its homebase. If, however, you object to such monitoring, or suspect that it is more intrusive than documented (and much of it isn't documented at all), then Spybot Search and Destroy can help you identify such types of software, and eliminate it. Some of the associated programs may then quit functioning, but maybe there are better alternatives anyway, than a program that has a spyware component.
Spybot S&D Home page

Download page

Direct Download v1.6

Pricelessware is another list of free software, if you are looking for some goodies not listed here.