function choseRandom(range) {
	if (Math.random) {
		return Math.round(Math.random() * (range-1));
	}else {
		var now = new Date();
		return (now.getTime() / 1000) % range;
	}
}

var nImages = 20; // Total number of images
var ranimage = new Array(nImages); // Array to hold the filenames
ranimage[0] = "images/header_home0.jpg";
ranimage[1] = "images/header_home1.jpg";
ranimage[2] = "images/header_home2.jpg";
ranimage[3] = "images/header_home3.jpg";
ranimage[4] = "images/header_home4.jpg";
ranimage[5] = "images/header_home5.jpg";
ranimage[6] = "images/header_home6.jpg";
ranimage[7] = "images/header_home7.jpg";
ranimage[8] = "images/header_home8.jpg";
ranimage[9] = "images/header_home9.jpg";
ranimage[10] = "images/header_home10.jpg";
ranimage[11] = "images/header_home11.jpg";
ranimage[12] = "images/header_home12.jpg";
ranimage[13] = "images/header_home13.jpg";
ranimage[14] = "images/header_home14.jpg";
ranimage[15] = "images/header_home15.jpg";
ranimage[16] = "images/header_home16.jpg";
ranimage[17] = "images/header_home17.jpg";
ranimage[18] = "images/header_home18.jpg";
ranimage[19] = "images/header_home19.jpg";


window.onload=function()
{
	// check for DOM
	if(!document.getElementById || !document.createTextNode){return;}
	var choice = choseRandom(nImages);
	var oHeader = document.getElementById('header');
	oHeader.style.backgroundImage = 'url(' + ranimage[choice] + ')';
}