Computer Security/Viruses

Firewalls

Web Site Validator

Virus Bulletin
Microsoft Security
AVG Anti-Virus Home Page
--- Log In
--- Free AVG Anti-Virus Software
--- Free AVG Anti-Virus Software at CNET
--- Repair AVG Anti-Virus
--- Uninstall AVG Anti-Virus
ClamWin Free Anti-Virus (for Windows)
Malwarebytes' Anti-Malware
McAfee.com
--- Threat Center
Broadcom (Formerly Symantec)
F-Secure
Antivirus.com
EICAR (European Institute for Computer Antivirus Research)
--- EICAR Test File

Bugtraq
Carnegie Mellon University - SEI CERT Division

Computer Security
--- Have I Been Pwned?

ContentWatch.com
--- Content Cleanup

Spyware / Adware
--- Ad Aware
--- Spybot Search & Destroy