CSS - Div Contenedor

<div id="principal">
	<div id="menu"></div>
	<div id="contenedor">
		<div id="imagen"></div>
		<div id="noticia"></div>
	</div>			
</div>

#principal
{
	width:800px;
	margin: auto;
	position: relative;
	background-color: #000;	
}

#menu
{
	width: 160px;
	height: 100%;
	background-color: #222;
}

#contenedor
{
	width: 640px;
	background-color: #1E2229;
	position: absolute;
	top: 0px;
	left: 160px;
}

#noticia
{
	width: 90%;	
	padding: 10px;
}