For a client in the financial services sector, I recently had to identify some candidate products for use in automating the testing their WinForms and VC++/MFC Windows desktop applications. The applications are used for trading financial instruments, so correct operation is absolutely essential.
UPDATE: this 2019 post from Joe Colantonio has a newer list of testing tools for Windows Desktop apps. WinAppDriver, Winium, and White Framework seem to be the best options.
After a bit of investigation and digging round in the more murky reaches of my memory, I came up with the following list of test automation tools for Windows desktop applications: