@W3bbo:I am making quite a decent living as a WPF expert. Yes there are times when I create hybrid applications and use winforms controls, but the flexibility WPF gives in creating components far outweighs any other considerations.
For your basic applications you can use either. I am currently working on some drawing tools to annotate images and WPF is far much nicer to do this sort of thing than Winforms. The code is nicer to wrtite and maintain and the result is superior. And you can use these tools on any surface (lets say a listbox for example). Using the winforms controls on the datagrid is a non-starter.