Shields Up!

This site will probe some of the most commonly exploited ports on your machine to see if you are vulnerable.

AV-Comparatives

This site offers independent comparatives of Anti-Virus software.

Security Now

Steve Gibson from Shields Up! and Leo Laporte from TechTV take 20 to 30 minutes near the end of each week to discuss important issues of personal computer security (podcast and weekly security column).

Security Developer Center

Microsoft's main MSDN security site for software developers.

Microsoft Security and Privacy Site

The main MS site for home users with bulletins and such.

Windows Update Site

Scan your MS operating system to check for critical and non-critical updates.

Internet Storm Center

Internet Storm Center is a free service to the Internet community that gathers more than 3,000,000 intrusion detection log entries every day to create a sort of "weather report" on activity. Also contains many useful papers.

SANS InfoSec Reading Room

Featuring over 1193 orginal computer security white papers in 70 different categories. You must have a working PDF viewer installed to access the papers.

windowsecurity.com/

Extensive security resources including articles, tutorials and the ability to browse the latest Microsoft security bulletins, patches and SPs for any MS product.

governmentsecurity.org

Network security articles and hacking prevention resources for the government and general public including tutorials and a forum.

Computerworld Security Knowledge Center

Extensive security resources.

HackerWatch.org (Anti-Hacker Community)

This site is associated with the McAfee Personal Firewall. The site features Activity Maps based on date from firewalls that display targets and sources by region. You can also check to see if your network has generated traffic that indicates infection.

Home Network Security

"This document gives home users an overview of the security risks and countermeasures associated with Internet connectivity, especially in the context of �always-on� or broadband access services (such as cable modems and DSL). However, much of the content is also relevant to traditional dial-up users (users who connect to the Internet using a modem)."

Home Computer Security

Pretty basic stuff about installing and using anti-virus programs and firewalls etc.