A little history on WMI first.
Windows Management Instrumentation (WMI) is a component of the Microsoft® Windows® operating system and is the Microsoft implementation of Web-Based Enterprise Management (WBEM), which is an industry initiative to develop a standard technology for accessing management information in an enterprise environment. WMI uses the Common Information Model (CIM) industry standard to represent systems, applications, networks, devices, and other managed components. You can use WMI to automate administrative tasks in an enterprise environment.
Where applicable WMI can be used in all Windows-based applications, and is most useful in enterprise applications. System administrators can find information about using WMI on TechNet, and in various books about WMI.
Lots of folks may not know this, but, there is this great command line tool in Windows XP (yes !!Windows XP. Was originally written for Windows 2003 but is it released with Windows XP as well) and above (Windows 2003 and SBS 2003). WMIC.exe gives you access to WMI on your Windows machine. The information you could collect now is simple amazing.
Here is a link to "A Description of the Windows Management Instrumentation (WMI) Command-Line Utility (Wmic.exe)" support article at Microsoft.com
Microsoft's msdn website.