The instruction limit posted an article on how to (properly) use Windows Forms with XNA.

Here’s something I had some difficulty doing “gracefully” with XNA: force a custom render device and user controls in the window while still using the Game framework. It’s quite easy to initialize XNA in a Managed DirectX fashion but you lose the links to the graphics device manager, the content pipeline and a lot of very useful (and well written) code behind the Game class.

Thanks ziggy for the link!