A great intro to multiplayer, one of the best programming books out there,
This review is from: Programming Multiplayer FPS Direct X (Charles River Media Game Development) (Paperback)
This book is simply great, as stated in the title I think it's one of the most important game programming books out there, but I'll get to that later.
The book goes through the processes of creating a surprisingly good engine, most importantly it's very modular, and easy to integrate new components. Topics are covered which will serve you well for many other programming projects, such as finite state machines (for things other than AI), linked lists, resource management, and so on.
It's a good idea to be at least a little familiar with Direct3D before reading this book, as the 3D rendering side is pretty detailed, and goes into some really cool techniques like occlusion and octrees. A really handy trick this book teaches is how to use 3DS Max as a level editor.
I'd say this is a very good introduction to multiplayer, it covers DirectPlay pretty well (including critical sections, it's vital to learn about concurrency sooner or later) using the peer to peer model. Once you've got the hang of what's in the book, you can go on to implement a client-server model, client side prediction, lag compensation, and maybe even use sockets instead of DirectPlay.
Finally why I think this is the most important game programming book out there (or at least that I've ever read), it covers the importance of using an iterative/evolving design process. Believe me when I say that is an extremely important lesson to learn, and this is the first game programming book I've found that teaches it.