You can use DDE in Windows 2000. I am running 2000 and the examples ran fine on my computer. There is a catch though - you need to make sure to start the server before the client and then not stop the server until the client has been stopped. If you just want to communicate between two LabVIEW programs, you may look at other communication methods. DDE is pretty old so I would look at moving into something newer. For an application similar to the examples you are looking at, I would recommend checking out the datasocket examples.
