Usa esto, debe servir
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Documento sin título</title>
<style type="text/css">
body{
margin:0px;
padding:0px;}
.contenedor{
position:absolute;
width:500px;
left:50%;
margin-left:-250px;
background-color:#FFFF00
}
.contenido{
float:left;
background-color:#FF0000;
width:55px;
margin:5px;}
</style>
</head>
<body>
<div class="contenedor">
<div class="contenido">asdf asdf asdf asdf asdf asdf asdf</div>
<div class="contenido">qwer qwer qwer qwer qwer qwer qwer</div>
<div class="contenido">zxcv zxcv zxcv zxcv zxcv zxcv zxcv</div>
<div class="contenido">uiop uiop uiop uiop uiop uiop uiop</div>
</div>
</body>
</html>