アクセスごとに違う画像を表示し、画像毎に別のページへジャンプ

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title></title>
<script type="text/javascript">
<!--
function cngI(){
    arrI = new Array("1.gif","2.gif","3.gif","4.gif","5.gif");
    arrA = new Array("bg1.html","bg2.html","bg3.html","bg4.html","bg5.html");
    var num = arrI.length;
    var i = Math.floor(Math.random()*num);
    document.getElementById("img").src     = arrI[i];
    document.getElementById("img").onclick = function (){
        location.href = arrA[i];
    }
}
//-->
</script>
</head>
<body onLoad="cngI()">

<p><img src="dmy.gif" id="img" alt=""></p>

</body>
</html>