As a former Microsoft technical lead who was a part of the "core" Enterprise server support team I will tell you that this is the one book that is (still) handed out to all new members of our team!Within Microsoft server support this book is the architecture "bible".Also David and Mark's elegant shareware tools <http://sysinternals.com> were also the only 3rd party tools that were sanctioned for recommendation to Microsoft customers.This book is the defacto standard for all things relating to Windows architecture. Not always an easy read, but if you are persistent and just keep re-reading (which is what I had to do for a long time!) eventually it will sink in, and when it does you will understand (and appreciate) Windows on a very low level.Highly recommended!Vic Rozumnybtw- MS recently bought sysinternals and you will be redirected when you go to the site. Congrats guys.