Motion/distance sensors & Arduino for installa

Hi Arduinoers

In the next few months I'll be working on putting together a light and sound installation in one my University's most beautiful old buildings. We're looking at having an interactive element at ground level where people's actions/movements trigger changes in an LED projection and possibly in the sound.

My question is, can anyone give me a basic idea of what components would be required for this?

My understanding is that I'll need an LED projector, software (will MAX4Live suffice?), Arduino interface, speaker setup and, of course, a motion sensor of some sort.

Also, what kind of motion sensors should I be looking at? Links to suppliers are welcome.

Any help appreciated!

  • Joey