Pondering TDD in Microsoft .NET, Second Edition

I have been getting asked quite a bit lately about updating the Test-Driven Development book. A number of things have changed since the book was published. Among them is .NET 2.0 has shipped, Visual Studio Team System has an integrated unit testing tool, and most important of all there has been a great deal of learning on how to approach TDD in .NET. The last change is what compels me the most to think about updating the book. The first two things are minor in my opinion and do not warrant an update to the book.

If I were to update the book I would like to get feedback on which tool I should use in the examples (NUnit, VS Team System, or MbUnit, etc.). I imagine that no matter which tool was chosen there might be a chapter in the appendix on the other tools.