Actually Cogman, WPF is not just another xml format. You are allowed to design GUI's using XML (which get loaded and parsed, and MS creates the form for you) but all the XML is optional. I have a business app I'm working on that now has 40+ screens and I've never used a single XAML (XML) form for any of it...
Reason: You can use inheritance/polymorphism and other OO things with WPF if you do everything in classes. The hard part - learning how to do all the xaml stuff in code.
But, that said. WPF is not really all that hard to learn, but it does have a learning curve as it's way more flexible.
Personally I bought this book which I thought was fairly good, but it is hard to understand in some sections. Because with the xaml everything is done 'magically' and writing larger apps requires some real knowledge of whats going on, this book didn't really suffice, but it will help you get up and running. This book is mostly 95% done with XAML.
This book aplies to the first release of WPF but I haven't found anything changed in VS 2008 (not sure about VS 2010 as I don't have it yet).
http://www.amazon.com/Windows-Presen...3966211&sr=1-3