MP3 off a laptop

Hi,

So, I'm trying to set an arduino up so that a sensor detecting anything in front of it will have an MP3 song on my laptop turn on. I'm thinking, a sensor that sends a high/low signal to the laptop, and some sort of program that will turn the MP3 on or off.

Any help would be great, thanks!

Do it in processing. Use that to play the MP3 (there is a library to do this). Then use the Arduino to send the message from the sensor into processing. There are plenty of examples of how to get an Arduino to send stuff into processing.

If processing has a library, that would be the best way to do it.

I was going to suggest imitating a PS/2 keyboard and send commands to winamp (c for pause, v for forward for example), but that will be very cumbersome for selecting a song.

Is there a guide or anything on how to do this?

I'm pretty newbish with this all =/

have a look at the Processing Minim library: http://processing.org/discourse/yabb_beta/YaBB.cgi?board=os_libraries_tools;action=display;num=1175037473