Windows Security Resources

• Microsoft Home User Guidebook
• "Security At Home" (by Microsoft)

Apple Security Resources 

• Apple Mac OS X Security
• Apple Product Security

General Security Resources

• Secunia - Excellent website that tracks vulnerabilities, new viruses, and provides statistics and historical data.
• SANS Internet Storm Center - This webite provides information on threats, trends, and overall Internet health. The handler-on-duty daily diaries provide excellent tips and other information.