var songs = new Array();
songs[0] = "song1.mp3";
songs[1] = "song2.mp3";
songs[2] = "song3.mp3";
songs[3] = "song4.mp3";

function changeSRC(num)
{
var useObject=typeof window.pageXOffset!='undefined';   
   
var p = document.getElementById('myplayer');
var d = document.getElementById('player');
var em = document.createElement(useObject?'object':'embed');

em.setAttribute('autostart', 'true');
em.setAttribute('autoplay', 'true');
em.setAttribute('hidden', 'true');
em.setAttribute('width', '0');
em.setAttribute('height', '0');
em.setAttribute(useObject?'data':'src',songs[num]);

em.id='myplayer';
d.replaceChild(em,p);

return true;
}