If you would like to test your windows GUI, try this Test Automation Fx.
You will get a new project in Visual Studio 2005 and 2008 and a designer to create your test project.
Then you record some clicks in your application to test. The designer generates C# or VB.NET code.
You can run the test to verify that your application behaves ;o)
It's nice that the output is .NET code so we can make adjustment if we need to. And even better, the recorded clicks doesn't only use stupid coordinates, but it identifies and finds buttons by name :o) So it could handle some changes without breaking the tests.
It works for both native and .NET applications.
It's a beta, but definitely worth looking at.