function swapPic()
     {
     if(document.getElementById)
                 {
                 var thePicture=document.getElementById("header") ;
                 var picPath="images/jpg/header_0"+rnd(7)+".jpg" ;
                 thePicture.style.background="url("+picPath+")" ;
                 }
     }
     
function rnd(n)
     {
     return Math.floor(Math.random() * n) + 1;
     }