Fantastic news, I got my box of complimentary copies of Professional Visual Studio Team System which is now on-sale in the UK as well as the US, so go get your copy :)
It looks like a great book, especially Chapter 6 which is the DSL Tools Chapter that I authored, it's based on the Feb CTP of DSL Tools which you can get here.
I've had a chance to look at all 3 of the major Team System books, and this is my personal opinion (I'm trying not be be biased! :)
Software Engineering with Microsoft Visual Studio Team System by Sam Guckenheimer is a fantastic looking book (Haven't had a chance to read it all yet), unlike the other books that concentrate on the technology it focuses on the process and methodology aspect first which is crucial to all organisations and then details how Team System can help from that angle (A top down approach if you like).
Team System is a great set of technologies with some awesome features, but using it right to solve your organisational/project problems is the "ace card"
Professional Visual Studio Team System by a number of authors, me included. It covers in great depth all of the technical areas of Team System including Testing, Profiling, Source Control, SDM Designers, etc.
Pro Visual Studio Team System 2005 by Jeff Levinson and David Nelson, I've had a quick look at this book and it like the previous book covers all of the main technical areas but in my (quick read) view it covers them at a higher level so more friendly for a less dev-technical person.
In short, your organisation definately needs the Sam Guckenheimer book if your going to adopt Team System (get it implemented and used right), if you want deep technical details on Team System you want Professional Visual Studio Team System and if you want a higher level view you want Pro Visual Studio Team System 2005.