var banner = new Array();

banner.push('http://img138.imageshack.us/img138/1319/banieretest3.jpg');
banner.push('http://i21.servimg.com/u/f21/09/01/05/89/copie_14.jpg');
banner.push('http://i24.servimg.com/u/f24/15/24/57/39/bann_p10.jpg');
banner.push('http://i44.servimg.com/u/f44/15/24/57/39/animgz10.gif');
banner.push('http://img64.imageshack.us/img64/7157/nouveautest.jpg');

document.getElementById('i_logo').src= banner[Math.floor(Math.random()*banner.length)];

setInterval("document.getElementById('i_logo').src= banner[Math.floor(Math.random()*banner.length)];",15000);