var images = new Array();
var i=0;
images[i++]='<img src="/custom/banner/slf1.jpg" alt="" border="0" />';
images[i++]='<img src="/custom/banner/slf2.jpg" alt="" border="0" />';
images[i++]='<img src="/custom/banner/slf3.png" alt="" border="0" />';
images[i++]='<img src="/custom/banner/slf4.png" alt="" border="0" />';
var index = Math.floor(Math.random() * i);
document.write(images[index]);