img = new Array();

img[0] = "img/top-image.jpg";
img[1] = "img/top-image01.jpg";
img[2] = "img/top-image02.jpg";
img[3] = "img/top-image03.jpg";
img[4] = "img/top-image04.jpg";
img[5] = "img/top-image05.jpg";
img[6] = "img/top-image06.jpg";

n = Math.floor(Math.random()*img.length);

document.write("<img src='"+img[n]+"' border='0' alt='' width='852' height='297' />");