I've just started developing a WPF application. This is not my first WPF app, but it will be the first that needs some polish. I know quite a bit about the "plumbing" of WPF such as binding, etc., but very little about how to polish it up. I don't need a snazzy UI. I just need something that looks like a native Windows app. For instance, if the app runs on XP, I want it to look like an XP app and pick up the user's UI theme. Same thing on Vista, etc.
How can I do this?