Sound Installation w/ motion detectioin

Hi there,

I'm looking for ways to quickly implement a sound installation (art project, no budget). Essentially, I want to be able to sense proximity of a person (via ir sensors or similar), and have the computer playback from a range of different sound filesaccordingly. Now here are my questions:

• what scripting language (or other software) migt be useful here? I have limited experience with perl, javascript, and waaayyyy back some turbo pascal (does anybody still know what that is ...?) I need something easy to learn, able to playback sounds, and able to interact with outside data. Any recommendations?
  
• Hardware - I have an elderly laptop that could run the installation, but of course need to do some research on how to plug the sensors into the computer, read them out, and generate events from the data. hmm...

Any hints are very welcome! Thanks!