Depends. If you want the touch screen to work like a mouse, you could probably get a driver from the touchscreen manufacturer (or might be built into windows depending on your platform/setup) that would allow you program the touchscreen as if it were a mouse.
There are more advanced touch screen setups (mostly experimental I believe) that allow multiple inputs and more complex interactions than a mouse. Might want to check out IBM's JAKI (Java Information Kiosks) although I don't know what the limits/rights are for using it.