The book is the first one that I've encountered that explains, with good working examples, how to fundamentally extend Windows NT functionality through new system services, software interrupts, and ring 0 code.It also provides good explanations of the virtual memory and LPC facilities, with very helpful specific code examples.The book does have a version 1.0 flavor to it. The editing and publishing are mediocre and there are many other areas of NT that I would love to see the authors apply their impressive investigative skills to.If you are interested in understanding as much about the internals of NT as anyone that doesn't have access to the NT source code can, this book is well worth examining.