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

if (AdNumber==1)
{
 url="http://www.frostbyte.uk.net";
 Graphic="http://www.frostbyte.uk.net/banners/Anim2d_468x60.gif ";
 width = "468"
 height = "60"
}   

if (AdNumber==2)
{
 url="http://www.frostbyte.uk.net";
 Graphic="http://www.frostbyte.uk.net/banners/adsl-anim1_468x60.gif";
 width = "468"
 height = "60"
}  

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

document.write('<center>');
document.write('<a href=\"' + url + '\" TARGET=\"_top\">');
document.write('<img src=\"' + Graphic + '\" width=')
document.write(width + ' height=' + height + ' ');
document.write('border=1>');
document.write('</a>');
document.write('</center>');