Professional C# 2008 starts by reviewing the overall architecture of .NET in Chapter 1 in order to give you the background you need to be able to write managed code. After that the book is divided into a number of sections that cover both the C# language and its application in a variety of areas.
I'm in the process of upgrading to VS2008 and loved the 2005 version of this book so picked up the 2008 update. It's a broad language and framework reference, perfect for understanding what's available in .NET 3.5 and how to get started. My only complaint is that it could have used a "what's new" section or guide to separate out completely new technologies from those familiar from .NET 2.0. Not a big problem though, it's easy to skim through the old stuff and then pay attention when you reach something new. I'll probably pick up the 2010 version in 2015 or so ;)
Flavored for c++ programmers converting to c#, this book gives great background on c# and the .net framework. I especially loved the chapters on memory and the CLR. There are some weak points where the authors don't describe a particular section as well as they could, but overall this is a fantastic book and wonderful c# reference.