var mess = new Array('<a href="http://www.upandrunningwatford.co.uk/" target="_blank"><img src="http://www.stalbansstriders.com/images/urw.jpg" align="center" width="142" height="49" border="0"/></a>','<a href="http://www.clifbar.co.uk" target="_blank"><img src="http://www.stalbansstriders.com/images/clif.jpg" border="0" /></a>');
var max = mess.length;
var num = Math.floor((Math.random() * max));
document.writeln(mess[num]);