Count the # of times VS.NET 2008 crashes on you during a day of WPF UI development and how many times it crashes on you during winforms development. (here it's almost impossible to do serious wpf development, it crashes alot even after sp1). Winforms also has a lot of mature controls. Sure it doesn't have the fancy shiny 3d stuff of wpf, but for LoB apps, you don't need these anyway. Add to that the blurry text issue of wpf, and you'll understand that wpf has a long way to go before it's mature enough to replace winforms.
