Regardless of your experience with the registry, this book can be of value to you. Despite the title, there are references in almost every section of the book on the Windows NT 4 registry, which can be helpful if you are working in a mixed environment or are coming from the NT 4 side of things.
The author starts the book by assuming you have no previous experience with the registry, and takes you on a 5 chapter tour, covering topics such as the history of the registry, how to navigate, what each part does, how to back it up and restore it, the different editors you can use, etc. From there, the book progresses for a couple of chapters on configuring policies - using the Policy Editor and GPO/OU policies within Windows 2000.
The author does include a surprising chapter in the middle entitled "Programming with the Registry" (Chapter 8) in which he covers many of the API calls for the registry and the Shell Utility, and then gives demos in C/C++, Perl and Visual Basic. My personal opinion is that that chapter is a little advanced for the book as a whole, but if you're not into it, it can be skipped without much loss to you.
The book also spends 2 chapters covering administration and tweaks (plus a great index section on the Group Policy Objects), and the final chapter documents what each hive in the registry does.
All in all, it's worth a read.