When to choose...WPF? Winforms? Silverlight? XBAPs?

Are you clear on when to use say WPF instead of Winforms? Or, just as importantly, when to use Winforms (e.g. for a more traditional LOB application)? Or that you can easily use both together? How does Silverlight compare to XBAPs?

David Chappell has written a white paper which describes the positioning of WPF vis a vis Winforms, explaining when to use which one, how to interop, and why Visual Designer for WPF doesn't (by design) offer every capability that's provided by the Windows Forms designer.

It's a quick way (35 pages) to understand not only WPF 3.5 features but also the whole MS UX continuum and how the different parts are related.