function banner(img_source,url,alt,chance) {
   this.img_source = img_source;
   this.url = url;
   this.alt = alt;
   this.chance = chance;
}
function display() {
   with (this) document.write("<A HREF=" + url + "><IMG SRC='" + img_source + "' WIDTH=468 HEIGHT=60 BORDER=0 ALT='" + alt + "'></A>");
}
banner.prototype.display = display;
banners = new Array();
banners[0] = new banner("http://www.webbox.cc/banners/advert.gif",
                       "http://www.netpostcode.com/advertise.html",
                        "Advertise your business on Netpostcode", 
                        10);						
banners[1] = new banner("http://www.webbox.cc/banners/realestate.gif",
                       "http://www.freeinfo.net.au target='_blank'",
                        "Absolutely independent solutions for all your Real Estate & Home Loan needs. Simply talk to us, obligation Free!", 
                        10);
banners[2] = new banner("http://www.webbox.cc/banners/domain.gif",
                        "http://www.planetdomain.com/webbox/ target='_blank'",
                        "Get your own domain name an be hosted now!",
                        10);
banners[3] = new banner("http://www.webbox.cc/banners/homeloan.gif",
                       "http://www.loans-online.com.au target='_blank'",
                        "Apply for your Home Loan online TODAY!", 
                        10);						
sum_of_all_chances = 0;
for (i = 0; i < banners.length; i++) {
   sum_of_all_chances += banners[i].chance;
}
function display_banner() {
   chance_limit = 0;
   randomly_selected_chance = Math.round((sum_of_all_chances - 1) * Math.random()) + 1;
   for (i = 0; i < banners.length; i++) {
      chance_limit += banners[i].chance;
      if (randomly_selected_chance <= chance_limit) {
         document.write("<A HREF=" + banners[i].url + "><IMG SRC='" + banners[i].img_source + "' WIDTH=468 HEIGHT=60 BORDER=0 ALT='" + banners[i].alt + "'></A>");
         return banners[i];
         break;
      }
   }
}