This free on-line 267-page book is an introduction to C# and the Microsoft .NET Framework for programmers who have experience with C or C++.
Version 1.1 of .NET Book Zero was uploaded on January 1, 2007, and contains numerous minor corrections of typos in version 1.0. Version 1.0 of the downloable code was uploaded on December 4, 2006, and has not changed with the new version of the book.
Download it here: http://www.charlespetzold.com/dotnet/
Thanks to Geert Verhoeven as I found this link in his blog entry FREE Book: Petzold's .NET Book Zero