Ich würde das ganze mit CSS machen in etwa so :
<html>
<head>
...
<style type="text/css">
body {
margin: 0;
padding: 0;
}
.conteneur {
position:absolute;
left: 50%;
top: 50%;
width: 800px;
height: 600px;
margin-top: -400px;
margin-left: -300px;
}
</style>
</head>
<body>
<div class="conteneur">
dein swf
</div>
</body>
<html>
<head>
...
<style type="text/css">
body {
margin: 0;
padding: 0;
}
.conteneur {
position:absolute;
left: 50%;
top: 50%;
width: 800px;
height: 600px;
margin-top: -400px;
margin-left: -300px;
}
</style>
</head>
<body>
<div class="conteneur">
dein swf
</div>
</body>