var ads = new Object();
var graphiclink = new Object();
var alt = new Object();

graphiclink[0] = 'xheader_mid_01.jpg';

graphiclink[1] = 'xheader_mid_02.jpg';

graphiclink[2] = 'xheader_mid_03.jpg';

graphiclink[3] = 'xheader_mid_04.jpg';

len=3;  // change to equal number of banners

var rnd1=Math.round(Math.random()*len); 

document.writeln('<IMG SRC="http://www.discandink.co.uk/header/'+graphiclink[rnd1]+'">');