WPF is quite a bit different than WinForms, and much more powerful. WPF is based on XAML or eXtended Application Markup Language, which is a form of XML that defines a form. So in WPF you work very closely with the XAML and the .cs files to create rich UI's.
People who work in WinForms usually find the transition to WPF painful (I do), the VisualStudio designer is pretty limited in what you can do with the WPF forms, but there are tools like Expression Blend that can make some pretty amazing effects.
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Here is a really good WPF tutorial site, run through a couple and see for yourself.[
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