ARDUINO MUSICAL CHAIRS? - help please

hi there
for this semesters industrial design project my collegues and i are builing an interactive arduino experience based on the idea of "musical chairs". Our idea is that we have three chairs with an array of sensors, so that when people interact with them (sit down, get up, swivel etc) they each play a beat.

we are just trying to find out what would be the best way to acheive this, as we are all new to arduino and what it can do.

any help would be MUCH appreciated!!

thanks
nathan

oh and heres a link to our project blog http://tandesign.tumblr.com/

How about these home made sensors, you can use them on the seats, backs or in front of the chairs.
http://www.thebox.myzen.co.uk/Hardware/MIDI_Footsteps.html