Was ist hieran falsch?
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html><head>
<script>if (navigator.appName != 'Microsoft Internet Explorer'){
<meta http-equiv=refresh content='0; URL=übersicht.htm'>}
else{
<meta http-equiv=refresh content='0; URL=netscape.htm'>
}</script>
</head>
<body>
<script>
document.write(navigator.appName);
</script>
</body>
</html>