var mess = new Array('<img src="images/banner.jpg" width="448" height="230">','<img src="images/banner2.jpg" width="448" height="230">','<img src="images/banner3.jpg" width="448" height="230">','<img src="images/banner4.jpg" width="448" height="277">');
var max = mess.length;
var num = Math.floor((Math.random() * max));
document.writeln(mess[num]);