var banner = new Array();

banner[0]='http://i374.photobucket.com/albums/oo182/CMDSonic/finalsx.png';
banner[1]='http://i374.photobucket.com/albums/oo182/CMDSonic/SX/sxrolfinal.png';
banner[2]='http://i374.photobucket.com/albums/oo182/CMDSonic/sxtrme.png';

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