<!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" xml:lang="ru" lang="ru" dir="ltr">
<body>
<style>
.Wrap {
position:relative;
background-color:#D6F5FF;
}
.left {
width:200px;
height:400px;
border:1px solid red;
}
.right {
top:0;
bottom:0;
margin-left:220px;
width:200px;
position:absolute;
border:1px solid blue;
}
</style>
<div class=Wrap>
<div class=left>Левая</div>
<div class=right>Правая, ровняем под левую</div>
</div>
</body>
</html>