Alla fine ho risolto con questo script:

<script>
if (!document.layers)
document.write('<div id="divStayTopLeft" style="position:absolute">')
</script>

<layer id="divStayTopLeft">


[img]immagini/banner.gif[/img]

[img]immagini/banner.gif[/img]

[img]immagini/banner.gif[/img]


</layer>


<script type="text/javascript">

/*
Floating Menu script- Roy Whittle (http://www.javascript-fx.com/)
Script featured on/available at http://www.dynamicdrive.com/
This notice must stay intact for use
*/

//Enter "frombottom" or "fromtop"
var verticalpos="frombottom"

if (!document.layers)
document.write('</div>')

function JSFX_FloatTopDiv()
{
var startX = 30,
startY = 255;
var ns = (navigator.appName.indexOf("Netscape") != -1);
var d = document;
function ml(id)
{
var el=d.getElementById?d.getElementById(id):d.all?d.a ll[id]:d.layers[id];
if(d.layers)el.style=el;
el.sP=function(x,y){this.style.left=x;this.style.t op=y;};
el.x = startX;
if (verticalpos=="fromtop")
el.y = startY;
else{
el.y = ns ? pageYOffset + innerHeight : document.body.scrollTop + document.body.clientHeight;
el.y -= startY;
}
return el;
}
window.stayTopLeft=function()
{
if (verticalpos=="fromtop"){
var pY = ns ? pageYOffset : document.body.scrollTop;
ftlObj.y += (pY + startY - ftlObj.y)/8;
}
else{
var pY = ns ? pageYOffset + innerHeight : document.body.scrollTop + document.body.clientHeight;
ftlObj.y += (pY - startY - ftlObj.y)/8;
}
ftlObj.sP(ftlObj.x, ftlObj.y);
setTimeout("stayTopLeft()", 1);
}
ftlObj = ml("divStayTopLeft");
stayTopLeft();
}
JSFX_FloatTopDiv();
</script>