Interactive Window Display Idea

I am designing an interactive window display with LED lights, and need some help determining which components would be best suited to my needs (this is my first project btw). The display will be in a mall setting (multiple user inputs), behind glass, and feature 5 separate led lights that light up and simultaneously play a short audio clip when someone walks by the sensors. The idea is that you could trip the sensors by walking, or even "play" the display almost like the strings of a guitar by dancing/ moving in front of it. I have done a little research, and my thoughts for inputs so far are:

  1. Using 5 motion sensors (probably microwave as I think IR will not transmit through the glass), each triggering one light/sound combination. How these hook into the adruino I don't know.
  2. Using a camera (possibly with a PIC or AVR included) as a motion sensor. I found this ARDUINO EYE SHEILD: http://www.davidchatting.com/arduinoeyeshield which lets you hook up a camera. This could possibly work?

I have no idea what I am doing, so any help / ideas are much appreciated.

Thanks!