mp3 file preloader

Hi guys,
I have a simple jukebox section on site and need a preloader,
to let the user know that something actually is happening when they click on play, and wait for mp3 to load.
just wondering if anyone here has any ideas on best way to create preloader based on the code I am using (which is as simple as can be!)
here is the code:

var attach_song:Sound = new Sound();
attach_song.loadSound(“audio/song1.mp3”, false);

playsong.onRelease = function() {
attach_song.start();
stopsong.onRelease = function() {
attach_song.stop();
};