CodeProject has an excellent series on WPF by Josh Smith
Part 1 (XAML): Learn about XAML and how it is used in WPF applications.
Part 2 (Layout): Learn about layout panels and how they are used to construct user interfaces.
Part 3 (Data binding): Learn how WPF data binding works and how it can be used.
Part 4 (Data templates and triggers): Learn how data templates and triggers work and how they can be used.
Part 5 (Styles): Learn about how UIs can be styled in WPF.