var NumberOfAds = 3;
var now = new Date()
var sec = now.getSeconds()
var AdNumber = sec % NumberOfAds;
AdNumber +=1;

if (AdNumber==1)
{
 url="http://www.simmate.co.uk/default.asp?UKPSRef=231";
 Graphic="http://www.dmclub.co.uk/banners/simmate468x60.gif";
 width = "468"
 height = "60"
}  

if (AdNumber==2)
{
 url="http://www.frostbyte.gb.com";
 Graphic="http://www.frostbyte.co.uk/banners/mobiles-468x60-anim1.gif";
 width = "468"
 height = "60"
}  

if (AdNumber==3)
{
 url="http://www.dmclub.co.uk";
 Graphic="http://www.dmclub.co.uk/banners/0207-468x60-anim1.gif";
 width = "468"
 height = "60"
}  



document.write('<a href=\"' + url + '\" TARGET=\"_blank\">');
document.write('<img src=\"' + Graphic + '\" width=')
document.write(width + ' height=' + height + ' ');
document.write('border=0>');
document.write('</a>');