function banner(imgSource,url,alt,chance) {
this.imgSource = imgSource;
this.url = url;
this.alt = alt;
this.chance = chance;
}
function dispBanner() {
with (this) document.write("<A HREF=" + url + "><IMG SRC='" + imgSource + "' WIDTH=150 HEIGHT=55 BORDER=0 ALT='" + alt + "'></A>");
}
banner.prototype.dispBanner = dispBanner;
banners = new Array();

banners[0] = new banner("/immagini/banner/daila150x55.jpg",
                        "http://www.dailapercussion.com target='_blank'",
                        "DA..ILA precedenza alla musica che è in te.",
                        30);
banners[1] = new banner("/immagini/banner/udu150x55.jpg",
                        "",
                        "Ululati dall&#039;Underground",
                        30);
banners[2] = new banner("/immagini/banner/Audioroma150x55.jpg",
                        "http://www.audioroma.net target='_blank'",
                        "Audioroma",
                        30);
banners[4] = new banner("/immagini/banner/zenith150x55.jpg",
                        "http://www.zenith-informatica.com target='_blank'",
                        "Zenith Informatica",
                        30);


sum_of_all_chances = 0;
for (i = 0; i < banners.length; i++) {
sum_of_all_chances += banners[i].chance;
}
function randomBanner() {
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].imgSource + "' WIDTH=150 HEIGHT=89 BORDER=0 ALT='" + banners[i].alt + "'></A>");
return banners[i];
break;
      }
   }
}