This site provides .Net, MFC, and Visual C/C++ tutorials and source code.
Desktop Engineer's Junk Drawer
Great site for news and information related to Windows systems management.
If you're interested in certification, check out this site.
A great site for certification resources including free practice exams.
Microsoft's TechNet Script Center
An awesome collection of tools and scripts for administrative management of your Windows network.
The Sysinternals newsletter provides you updates on what's new at Sysinternals, plus miscellaneous tips and information on Windows internals.
This a great source of Windows IT information and downloads.
FAQ for Windows
One of the best Windows NT/2K FAQ sites around.
Windows Guide Network
Technical resources and support for tweaking, managing and securing Windows using the registry, scripting and security.
Azius developer training offers courses on Windows 2000/NT/CE/9x device drivers and systems-level software.
David Solomon Expert Seminars, Inc.
Dave Solomon, coauthor of "Inside Windows 2000, 3rd Ed." (MS Press, 2000) offers public and private courses on Windows NT/2000 internals. Dave has access to the Win2K sources and development team so this course provides detailed information not available anywhere else.
HP Integrity Servers
The HP Integrity server portfolio provides flexible capacity, secured availability, and simplified management for your Windows environment-helping you meet your business needs while delivering a better return on IT .
Wintellect, which consists of some of the top names in Windows development, offers consulting and training for COM, Win32, and .NET technologies.
Advanced system monitoring, recovery, and repair tools.
Dr. Dobb's Journal
Embedded, Windows, Unix programming articles and source code.
Windows IT Pro Magazine
An excellent resource of information for implementing and supporting Windows NT-based installations. Mark is a contributing editor and regular columnist.
If you write applications for Windows 9x or Windows NT/2K then you need this book. John Robbins gives you numerous real-world tips and techniques to both help you debug and help you prevent bugs in the first place.
Inside the Windows 95 File System
Stan Mitchell's coverage of the Windows 95 file system environment is an introduction, with an emphasis on introduction, to the topic. As I learned while developing our full-featured NTFS for Windows 98 driver environment, the book lacks much of the information necessary to develop a production file system driver.
Programming Applications for Windows
Arguably the best book in its class, Jeff Richter does a masterful job of presenting multithreading, interprocess communication and synchronization, and other features of the Win32 API.
Programming the Microsoft Windows Driver Model
Walter Oney does a thorough job (with the collaboration of Microsoft's WDM team) of explaining the Windows Driver Model.
Programming Server-Side Applications for Windows 2000
Jeff Richter and Jason Clark provide the most comprehensive guide to writing Win32 services available. Topics covered include the event log, WMI, and service security.
Systems Programming for Windows 95
If you develop or plan on developing VxDs for Window 95/98 then you probably already have this definitive guide to writing native drivers for Microsoft's "other" operating system by Walter Oney. It includes coverage beyond the basics, including introductions to VSD and file system development.
Windows Internals, 4th Edition
Mark Russinovich (me) and Dave Solomon coauthored this definitive work on the internals of Windows 2000, XP and Windows Server 2003.
Windows NT File System Internals
Rajeev Nagar's book on file system development for Windows NT is the only published source of information on this very complex topic, and he does an excellent job of introducing the issues you'll run into if you work in this area. In addition, roughly the first half of the book serves as a good primer on kernel-mode driver devlopment.
Windows NT/2000 Native API Reference
Get the inside scoop on the native API with this reference. The text is terse, but the documentation is accurate. Although the author claims he didn't have access to source code, structure-field and function-parameter names bear just a little too close a resemblence to the actual definitions to be just a coincidence, according to people with legitimate source access.