Can you show us the web site you are working on, or a live demo? I can't quite understand what you want. You were asking on web design advice earlier, so I figured I would give it now.

Use HTML or XHMTL for content and CSS for structure, tables are for tabular data. Something like this would get you the desired effects, no tables included:
XHTML:
CODE
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<link href="stylesheet.css" rel="stylesheet" type="text/css" />
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>Tables are evil.</title>
</head>
<body>
<div id="container">
<div id="tab">
Main Features
</div>
<div id="space">
</div>
</div>
</body>
</html>
CSS:
CODE
#container {
height: 17px;
margin: 20px auto 0px auto;
width: 500px;
}
#space {
border-bottom: 1px solid #194173;
float: left;
height: 16px;
width: 400px;
}
#tab {
background: #194173;
border-bottom: 1px solid #194173;
color: #FFF;
float: right;
height: 16px;
text-align: center;
width: 100px;
}