var images = new Array()
images[0] = "images/header/sonic.png"
images[1] = "images/header/virtua_tennis_web.png"
images[2] = "images/header/super_monkey_web.png"

var x = Math.floor(Math.random()*3)

document.write("<div style=\"background:url('" + images[x] + "') no-repeat; height:125px; width:748px; margin-left:auto; margin-right:auto;\"></div>")