Automated UI testing a large c# forms app

I am working on a fairly complicated project. We have a c# forms app that has several layers of business logic, communicating with a c++ hardware management layer via a socket interface. We have unit test coverage of the c++ side, and the business logic, but acceptance testing of the forms app is a whole new world for me, as we have done exclusively web apps heretofore. Any suggestions on where to start? I looked at NUnitUI, but I'm not sure that it has enough depth to do what we need. I am looking for a suite to do automated UI testing. Also, I am okay with paying for the right solution if that is what I need to do. Thanks!