var banner = new Array();

banner[0]='http://i28.tinypic.com/nntnoz.jpg';
banner[1]='http://i55.tinypic.com/2z6xqbc.jpg';
banner[2]='http://i28.tinypic.com/nntnoz.jpg';
banner[3]='http://i53.tinypic.com/54umx4.jpg';
banner[4]='http://i28.tinypic.com/nntnoz.jpg';

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