codice:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<script type="text/javascript" language="javascript">
<!--
function loadpage() {
browver= parseInt(navigator.appVersion);
browtype = navigator.appName;
browsertype = "old";
if (browtype == "Netscape" && !(browver < 3)) {
browsertype = "new";
}
if (browtype == "Microsoft Internet Explorer" && !(browver < 4)) {
browsertype = "new";
}
if (browsertype == "new") {
thetimer = setTimeout("changeimage()", 3000);

thetimer2 = setTimeout("changeimage2()", 3000);

banneradcode = 0;
bannercode2=0;

listofimages = new Array(3);
listofimages[0] = new Image(468,60)
listofimages[0].src = "banner-0.gif"
listofimages[1] = new Image(468,60)
listofimages[1].src = "banner-1.gif"
listofimages[2] = new Image(468,60)
listofimages[2].src = "banner-2.gif"

listofimages2 = new Array(3);
listofimages2[0] = new Image(468,60)
listofimages2[0].src = "banner2-0.gif"
listofimages2[1] = new Image(468,60)
listofimages2[1].src = "banner2-1.gif"
listofimages2[2] = new Image(468,60)
listofimages2[2].src = "banner2-2.gif"
}
}

function changeimage(){
if (browsertype == "new") {
banneradcode = banneradcode + 1
if (banneradcode == "3") {
banneradcode = 0
}
imagesource = "banner-" + banneradcode + ".gif"
window.document.bannerad.src = imagesource
thetimer = setTimeout("changeimage()", 5000);
}
else if (browsertype == "old") {
}
}
function changeimage2(){
if (browsertype == "new") {
banneradcode2 = banneradcode2 + 1
if (banneradcode2 == "3") {
banneradcode2 = 0
}
imagesource = "banner-" + banneradcode2 + ".gif"
window.document.bannerad2.src = imagesource
thetimer = setTimeout("changeimage()", 5000);
}
else if (browsertype == "old") {
}
}

function changepage() {
if (browsertype == "new") {
if (banneradcode == 0) {
newlocation = "http://www.html.it"
}
else if (banneradcode == 1) {
newlocation = "http://www.html.it"
}
else if (banneradcode == 2) {
newlocation = "http://www.html.it"
}
location = newlocation
}
else if (browsertype == "old") {
location = "http://www.html.it"
}
}
function changepage2() {
if (browsertype == "new") {
if (banneradcode2 == 0) {
newlocation = "http://www.html.it"
}
else if (banneradcode2 == 1) {
newlocation = "http://www.html.it"
}
else if (banneradcode2 == 2) {
newlocation = "http://www.html.it"
}
location = newlocation
}
else if (browsertype == "old") {
location = "http://www.html.it"
}
}
// --></script> 
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>Documento senza titolo</title>
</head>

<body bgcolor="white" vlink="blue" link="blue" onload="loadpage()">



<a href="java-script:changepage()">
[img]banner-0.gif[/img]
</a>


<a href="java-script:changepage2()">
[img]banner2-0.gif[/img]
</a>

</body>
</html>
così dovrebbe andare