Learning WPF

I'm new to WPF. What I understand is that with WPF it is possible to create much more "nicer"-looking UI than with winforms.

I have an existing winform project coded with VB.NET and I would like to learn how to update the user interface to a WPF equivalent. The business and data access logic should still run as it is now and I only would like to change the UI side of the application. I'll also have to create new custom controls, probably using Expression Blend or similar tools.

What would be the best places to start learning the WPF with that kind background?