Here are a few sites that I find very useful in my day-to-day system administration. Feel free to click around. They are not all highly technical so if you ever need a break from the details and would rather look at the big picture, these are the places to check out.

SpyBot S&D - Free Spyware Remover
ClamWin - Free Antivirus Package
Snort - Free Intrusion Detection System
SPF (Sender Policy Framework)

Microsoft Resources
Technet Security
Security Bulletins
Microsoft Baseline Security Analyzer
Microsoft Script Center
Microsoft Partner Program
Microsoft Connections Live Seminars
Microsoft Public Newsgroups
IT Professional Blogs
Microsoft Exchange Team Blog
Eileen Brown
Susan Bradley
Susanne Dansey
Brian Kruse
Robert Scoble
Kevin Remde
John Howard
Christopher Rue
Tavis Patterson
Tim Barrett
TS2 Community

Vlad Mazek is not responsible for the content provided by these third-party web sites and is in no way affiliated with them.