Free security software downloads for Windows

Also mentioned today:
>> Download free Windows security patches from Windows Update
>> Zone Alarm: Free firewall software
>> AVG: Free Anti-Virus Software
>> Avast: Free Anti-Virus Software
IMPORTANT: Please note that free firewall and anti-virus software is usually unsupported, so install and use at your own risk. If you want a product which includes free technical support, expect to pay for the software. You'll find reviews of a range of windows security products (both free and paid-for) at the following links
>> Web User: AntiVirus software reviews
>> Web User: Firewall reviews
>> Web User: Anti-Spyware software reviews

>> Website of the Day: More online security links