se ho capito bene, puoi provare con i margini negativi
codice:
<!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" lang="it" xml:lang="it">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>xhtml 1.0</title>
<style type="text/css">
* { margin: 0; padding: 0;}
#cnt { padding-left : 200px; background: #c66; } /* rosso */
#left { float: left; display: inline; margin-left: -200px; width: 200px; background: #6c6; } /* verde */
</style>
</head>
<body>
<div id="cnt">
<div id="left">
div fisso
</div>
Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet
dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper
suscipit lobortis nisl ut aliquip ex ea commodo consequat.
</p>
Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet
dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper
suscipit lobortis nisl ut aliquip ex ea commodo consequat.
</p>
</div>
</body>
</html>