function rollHeaders() {
headerArray = new Array("/media/67824/header1.jpg","/media/67834/header3.jpg","/media/67839/header4.jpg","/media/67844/header5.jpg","/media/67849/header6.jpg","/media/67854/header7.jpg","/media/67859/header8.jpg");

which = Math.floor(7*Math.random())
which = headerArray[which];

  document.getElementById("Header").style.backgroundImage = "url('" + which + "')";
}