var bgUrls=["http://www.tangdigital.com/bg/bg0.gif","http://www.tangdigital.com/bg/bg1.gif","http://www.tangdigital.com/bg/bg2.gif","http://www.tangdigital.com/bg/bg2.gif","http://www.tangdigital.com/bg/bg2.gif"];


jQuery(document).ready(function(){
    var bgUrl=bgUrls[Math.floor(Math.random()*bgUrls.length)];
		jQuery('html').css('background', 'url(' + bgUrl + ') repeat fixed '); 
		jQuery('body').css('background', 'url(' + bgUrl + ') repeat fixed'); 
 
});