In time for the upcoming Visual Studio 2005 and .NET v2.0 Beta 2 release, the updated version of my ADO.NET and System.Xml book has now been published. See this book list for more information and where to download the code examples from. Alternatively just buy a copy so that I can feed my children and bribe my wife to convince her that the hours of writing were worthwhile.
If you bought a copy of the first version of this book, this version is a total re-write and twice as thick, reflecting that a year and a half changes a product in many ways. Given that this is on ADO.NET it also covers features from SQL Server 2005 and complements Bob Beauchemin's et al book A First Look at Microsoft SQL Server 2005 for Developers. I would not buy this book unless you have a sufficient understanding of either ADO.NET or System.Xml today, since this simply covers the delta from .NET v1.1 to .NET v2.0. For example there is a chapter on the XPathNavigator and XmlDocument class enhancements, but you have to understand the existing API to get the most benefit from this. The MSDN2 documentation here is a good place to start (if you want to know more about MSDN2 read this blog entry).
If you feel compelled to provide feedback, I would love to hear suggestions as to what to add or improve especially for the chapters on System.Xml.