window.addEventListener?window.addEventListener('load',function()
{
ray.rand('thisCell');
},false):
window.attachEvent('onload',function()
{
ray.rand('thisCell');
}); // FF : IE1

var ray=
{
bgArr:['url(td-bg1.jpg)','url(td-bg2.jpg)','url(td-bg3.jpg)','url(td-bg4.jpg)','url(td-bg5.jpg)','url(td-bg6.jpg)','url(td-bg7.jpg)','url(td-bg8.jpg)'], // Background you wish to show on the cell
rand:function(el)
{
var num = Math.floor(Math.random()*this.bgArr.length);
this.getID(el).style.background=this.bgArr[num];
},
getID:function(el){return document.getElementById(el);}
}