Можно так:
Код:
<!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>
****<title>3px</title>
****<style type="text/css">
****/*<![CDATA[*/
****#left{float: left; width: 150px; background-color: green; height: 50px;}
****#right{background-color: gray; height: 50px; margin-left: -150px; float: right; width: 100%;}
****#right div{margin-left: 150px;}
****/*]]>*/
****</style>
</head>
<body>
****<div id="right"><div></div></div>
****<div id="left"></div>
</body>
</html>