Ho un problema... non riesco a centrare un contenitore (div) pre firefox.

In IE7 risulta centrato in firefox no. Sono alle prime armi e il box da centrare è #sitebody che è il div che contiene tutto il sito.

codice:
@charset "utf-8";
body {
	margin: 0;
	background-color: #FFFFFF;
	text-align: center;
	background-image: url(../image/sfondo.jpg);
	background-repeat: repeat-x;
}
#menu {
	position:relative;
	width:auto;
	height:32px;
	z-index:2;
	visibility: visible;
	left: auto;
	top: 0px;
	background-attachment: scroll;
	background-image: url(../image/Menu.jpg);
	background-repeat: repeat-x;
	background-position: left top;
	bottom: 0px;
	text-align: center;
}
#sitebody #menu td {
	height: 32px;
	border: 0;
	margin: 0;
	padding: 0;
	text-align: center;
}
#sitebody #bottom em {
	font-family: Arial, Helvetica, sans-serif;
	font-size: 14px;
	font-style: italic;
	line-height: normal;
	font-weight: normal;
	font-variant: normal;
	color: #FFFFFF;
}


#header {
	position:relative;
	width:auto;
	height:113px;
	z-index:1;
	background-attachment: scroll;
	background-image: url(../image/Logo.jpg);
	background-repeat: no-repeat;
	background-position: center top;
	top: 0;
	visibility: visible;
}
#sitebody {
	position:relative;
	left:0px;
	top:0px;
	width:762px;
	height:100%;
	z-index:1;
	background-color: #FFFFFF;
	border-right-width: 1px;
	border-left-width: 1px;
	border-right-style: groove;
	border-left-style: ridge;
	border-right-color: #000000;
	border-left-color: #000000;
}
#bottom {
	position:relative;
	width:auto;
	height:61px;
	z-index:2;
	background-color: #000000;
	background-image: url(../image/Footer.jpg);
	background-repeat: repeat-x;
	right: 0px;
}
#pagecont {
	position:relative;
	left:0px;
	width:auto;
	height:400px;
	z-index:2;
	background-color: #FFFFFF;
}