Windows Vista Security Blog
http://blogs.msdn.com/windowsvistasecurity
The Windows Vista Security blog is a good resource for new information regarding Windows Vista security and related features.

Internet Explorer Blog
http://blogs.msdn.com/ie/
The Internet Explorer Blog is a good reference point, direct from the source, for all areas of Internet Explorer. The blog details what the team is working on, how they make decisions, why certain parts of Internet Explorer work the way they do, as well as good tips and tricks.

Windows Server Division WebLog
http://blogs.technet.com/windowsserver/default.aspx
The Windows Server Division blog allows the IT community to have direct contact with the members of the Windows Server team and learn about its latest activities and projects, as well as a plethora of useful information.

Michael Howard’s Web Log
http://blogs.msdn.com/michael_howard/
Michael, who calls himself a “simple software security guy at Microsoft,” is a senior security program manager. His blog focuses on security and privacy.

Kim Cameron’s Identity Weblog
http://www.identityblog.com/
Kim, an architect of identity and access in the Connected Systems Division at Microsoft, blogs about the evolution of Active Directory® Federation Services, Identity Integration Services, InfoCard and Microsoft’s other Identity Metasystem products. The influential Laws of Identity, which Kim published, are also featured on his blog.

Ian Hameroff’s Blog
http://blogs.technet.com/ianhamer
Ian’s blog covers Windows Server networking topics with a focus on both today’s technologies and the evolution of networking. This includes IPsec, IPv6, Network Access Protection, scalable networking, secure clients, secure wireless connections, server and domain isolation, Windows Firewall and Windows networking.

Jeff Jones Security Blog
http://blogs.technet.com/security/
Jeff Jones is a Strategy Director in the Microsoft Security Technology Unit, part of the team trying to make all Microsoft products more secure. His blog "is for discussing all things with respect to computer, network and information security."