var banners = 4;
var change = 15;
var o = 0;

function ad(url,hrf,w,h,alt){
 this.url    = url;
 this.hrf    = hrf;
 this.width  = w;
 this.height = h;
 this.alt    = alt;
}

ads = new Array();
ads[1] = new ad( "banner/observer.gif","http://www.observer.hu",120,240," ");
ads[2] = new ad( "banner/hirvad.gif","http://www.hirvadasz.hu",120,240," ");
ads[3] = new ad( "banner/netaukcio.gif","http://www.netaukcio.hu/cgi-bin/index.pl",120,240," ");
ads[4] = new ad( "banner/b33.gif","http://www.irodaweb.hu/",120,240," ");               

function rotate(){
 o++;
 o = (o > banners) ? 1 : o;
 with(ads[o]){
  var tmp = '<a href="'+hrf+'" target="_blank"><img src="'+url+'" alt="'+alt+'" width="'+width+'" height="'+height+'" border="0">'+'</a>';
 }
 banner.innerHTML = tmp;
 window.setTimeout("rotate()",change*1000);
}

window.onload = rotate;