var banner = new Array();

banner.push('http://img822.imageshack.us/img822/2773/ban1j.jpg'); banner.push('http://img686.imageshack.us/img686/6533/ban3yz.jpg'); banner.push('http://img841.imageshack.us/img841/1402/ban4.jpg'); 
banner.push('http://img831.imageshack.us/img831/7588/ban2wk.jpg');


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

setInterval("document.getElementById('logo').firstChild.src= banner[Math.floor(Math.random()*banner.length)];",7000);