Mark Russinovich might be the best mind at Microsoft. Clear spoken, he makes even the most complicated topics somewhat understandable to the rest of us. I would give up my next child to spend some time with him (that's a figure of speach).
PsTools, Filemon, and Regmon not only simplified my life, but gave some insight into what my network was really all about.
We need more of this guy on channel 9, he is the great communicator of the IT world!!!