codice:
<html>
<head>
<title>mouse follower</title>
<script type="text/javascript">
<!--
var NN4=(document.layers)?1:0;

function el(idx){
	return (NN4)?document.layers[idx]:(document.all)?document.all[idx].style:document.getElementById(idx).style;
}

function getMousePosition(e){
	if(!e) e=window.event;
	var mouseX=(e.pageX)?e.pageX:e.clientX+document.body.scrollLeft;
	var mouseY=(e.pageY)?e.pageY:e.clientY+document.body.scrollTop;

	el('follower').top=mouseY+((!NN4)?'px':'');
	el('follower').left=mouseX+((!NN4)?'px':'');
}

if(NN4) document.captureEvents(Event.MOUSEMOVE);
document.onmousemove=getMousePosition;
//-->
</script>
</head>
<body>
<div id="follower" style="position:absolute;top:0px;left:0px;z-index:100">[img]immagine.gif[/img]</div>
...contenuto...
</body>
</html>
se il documento ha un doctype valido lo script va modificato
ciao