Writing books on beta products is probably the most painful thing that you can ever endure even if you are in the product team (or was as in my case). I finally finished up the last XML chapter in the beta version of ADO.NET and System.Xml V2. It is a vast brain dump of the delta between V1.1 and V2.0 for System.Xml coupled with the numerous changes since the PDC 2003 preview release. However I was not able to cover the #1 feature enough of System.Xml V2.0 - performance. This will have to wait for any potential future final version of the book depending on sales of this one of course. All I can say is that you will not be disappointed - the XML team has done an incredible job. Every component is significantly more performant and more performance improvements will happen between now and RTM. I just saw the new perf numbers for the XmlDocument (DOM) class scenarios (load, edit, delete, insert, save etc) and they have shown an impressive leap. Sun came out at the beginning of the year bashing the performance of the XML support in .NET. I cannot wait for them to run their numbers again on V2.0 and once it ships that they will "go dark" on perf for a long time. Simply by adopting the Beta 2 release any XML processing that you have will be screamingly fast.