Initially I didn't liked Windows Vista. A resource hog, some incompatibilities... But I had to use it at work so I installed it and worked with it for two months. After that, I really like the security features it has, but I felt like missing more details about specific topics... So I decided to buy this book.
Writing Secure Code for Windows Vista comes as a, mostly C++ oriented (although contains some C# examples), "how to use all new features" book. Very well structured, with lots of code examples, best practices, direct to the topic, and one thing I liked a lot: very sincere. If something is working bad, the authors state it clearly (for example, the Windows Firewall API, which has bugs), and they even provide workarounds to avoid them.
Down to the content, the book covers a lot of topics: New safer C functions, banned APIs, new APIs, UAC, token manipulation, integrity levels, code signing, virtualization, buffer overrun defenses, IPv6, Secure Socket extensions, Windows Firewall (Vista version, of course), IE7 security mechanisms & defenses (very interesting), Windows services development best practices, protected mode API and DEP, and the new CNG (Cryptography API: Next Generation).
Even if you don't usually develop with C++ I highly recommend this book. With it you will learn a lot about all the new security features of Vista. You just need some basic knowledge of standard Windows security features and some C++/API programming.