windows - How would one programmatically kill an application?

I'd like to write a little app to loop through a directory of powerpoint presentations. I figure a likely solution would perhaps require simply running powerpoint for say 30 mins and then killing it before running powerpoint again with another presentation.

The idea is that it would be unmanaged and other people could simply drop a new powerpoint file in the directory and it would eventually be displayed. My target deployment is to an LCD TV in a hallway at the office so the PC is unmanned.

Starting powerpoint via an application is easy, the sticking point at the moment is how to kill a running powerpoint (started from the same app).