Microsoft Corporation. Designing for the User Experience. Redmond, WA: Microsoft Press, 1999.
I discussed this book in Chapter 1, so I'll keep my comments short here. I believe that this book is the single best source of Windows user interface information, and I refer to it often. Then why do I rank it second? While Designing for the User Experience does an excellent job of defining standard Windows appearance and behavior, it doesn't give you the understanding and insight that Cooper's book does. Designing for the User Experience explains what and how, and About Face explains why. I believe mastering why is ultimately more important.
This is a must-have book.