- Feasibility - it is entirely possible to do what I mean to do, right?
Yes no problem
The simplest way is to use MIDI and then use the MIDI messages to trigger sounds in your PC. Look at an application called "hairless", this software runs on your PC and converts the serial output from the Arduino into an internal MIDI bus in your PC. The you just direct this but towards your MIDI player or sound generator. I use Garage Band to do this.
This project shows how to do it, all be it with different forms of triggering the notes.
http://www.thebox.myzen.co.uk/Hardware/Pendulum.html