 <p>I've looked at the MSDN page... it said NtQuerySystemInformation() is an OS internal proc, and that we're not recommended to use it:</p> <blockquote> <p>The NtQuerySystemInformation function and the structures that it returns are internal to the operating system and subject to change from one release of Windows to another. To maintain the compatibility of your application, it is better to use the alternate functions previously mentioned instead.</p> </blockquote>