Imgs = new Array();
Imgs[0] = "/images/banner_r00.gif";
Imgs[1] = "/images/banner_r01.gif";
Imgs[2] = "/images/banner_r02.gif";
Imgs[3] = "/images/banner_r03.gif";
Imgs[4] = "/images/banner_r04.gif";

function RandomChange(){
ImgAddr = Imgs[Math.floor(Math.random() * Imgs.length)];
document.images["banners"].src = ImgAddr;
}