// JavaScript Document
<!-- 
if (document.getElementById) { window.onload = swap };

function swap() {
var numimages=3;
rndimg = new Array("images/body_bkgd.jpg", "images/body_bkgd2.jpg", "images/body_bkgd3.jpg"); 
x=(Math.floor(Math.random()*numimages));
randomimage=(rndimg[x]);
document.body.style.backgroundImage = "url("+ randomimage +")"; 
}
//-->