ranimg = new Array(); 
ranimg[0]='images/bg0.jpg'; 
ranimg[1]='images/bg1.jpg';
ranimg[2]='images/bg2.jpg';
ranimg[3]='images/bg3.jpg'; 
ranimg[4]='images/bg4.jpg';
ranimg[5]='images/bg5.jpg';
xx = Math.floor(ranimg.length * Math.random());
document.write ('<style type="text/css"><!--#wrapper {background-image: url("'+ ranimg[xx] +'");}--></style>');