Centrare il Div float sia in Firefox che in Explorer

<div id="container">
	<div id="header">
		contenuto
	</div>
	
	<div id="corpo">
		<div id="content">
        		contenuto
		</div>

		<div id="menu2">
			contenuto
		</div>
		
		<div id="varie">
			contenuto
		</div>
	</div>
</div>

body {
	margin: 0;
	padding: 0;
	text-align: center;
	background: #FF0000 url(../xxx/body.jpg) repeat-x center top;
}

#container {
	width: 800px;
	margin: auto;
	background-position: center;
	background-repeat: repeat-y;
	background-image: url(../xxx/container.jpg);
	text-align: left;
}

#header a{
	position:relative;
	display: block;
	width: 800px;
	height: 223px;
}

#header a span{
	position: absolute;
	width: 100%;
	height: 100%;
	background-image: url(../xxx/header.jpg);
	cursor: pointer /*regola per IE*/;
}
#corpo {
	width: 800px;
	float: right;
	display: inline;
}

#content {
	float: right;
	display: inline;
	width: 550px;
	background: transparent;
	color: #000;
}

#menu2 {
	float: right;
	display: inline;
	width: 180px;
	background: transparent;
	color: #000;
	font: italic bold 13px Georgia, "Times New Roman", Times, serif;
	margin-right: 15px;
	letter-spacing: -2px;
	word-spacing: 2px;
	}
	
#varie {
	float: right;
	display: inline;
	width: 180px;
	background: transparent;
	color: #000;
	margin-right: 8px;
	text-align: center;
}