We have a product that runs as a windows service. And now we are thinking of adding a security layer as an add-on to the service.

The security layer should lock down the PC (not in the literal sense) but should restrict the users from using the PC to do other things other than use the functionality provided by the user interface that sits above our service. I will be responsible for this add-on project.

How should I go on about building this add-on? Does windows itself has this kind of feature which can be customized? I don't have any ideas on this. Your suggestions and inputs will be very useful. My choice of language is native C++. Don't know if Dot Net has capabilities that I can use as an advantage to my project. Any links will be also helpful. Please Help.