Center swf object

Im trying to center a swf file thats being written with swfobject but I can only center it to the top.
Anybody nows how to help me?

<!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" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>Pierce - test</title>
<script type="text/javascript" src="swfobject.js"></script>
<style type="text/css">
html {
/* hide from ie on mac \*/
 
}
 
#flashcontent {
position: relative;
align: center;
margin: auto;
width: 880px;
height: 410px;
}
/* end hide */
body {
background-color: #C2C2C2;
font-family: Arial, Verdana, sans-serif
font-size: 10px;
}
p{
font-size: 12px;
color: #000000;
}
#content {
margin-left: 100px;
margin-top: 100px;
width: 505px;
}
a{
color: #990000;
}
a:link {
color: #990000;
text-decoration: underline;
}
a:hover {
color: #FF0000;
}
</style>
</head>
<body>
<div id="flashcontent" align="center">
<div id="content"><p>Please turn on javascript in your browser settings and check if you have atleast flashplayer
7 installed on your computer.</br>Download the latest flashplayer for free from <a href="http://www.adobe.com/shockwave/download/download.cgi?P1_Prod_Version=ShockwaveFlash" target="_blank">www.adobe.com</a></p>
</div></div>
<script type="text/javascript">
// <![CDATA[
var so = new SWFObject("pierce.swf", "pierce","880", "410", "7", "#C2C2C2");
so.addParam("scale", "noscale");
so.write("flashcontent"); 
// ]]>
</script>
</body>
</html>