var imagesrc = new Array
(
	"/themes/index/styles/banner1.png",
	"/themes/index/styles/banner2.png",
	"/themes/index/styles/banner3.png",
	"/themes/index/styles/banner4.png",
	"/themes/index/styles/banner5.png",
	"/themes/index/styles/banner6.png"
); 

function changeBanner()
{
	var rnd = Math.floor(Math.random()*6);
	document.getElementById('banner').style.backgroundImage = "url(" + imagesrc[rnd] + ")";
}