You don't mention a few important details like:
- Is the layout fixed width?
- Are either or both of the columns fixed width?
Here's one possibility:
<html>
<head>
<style type="text/css">
html, body, div { margin: 0; border: 0 none; padding: 0; }
html, body, #wrapper, #left, #right { height: 100%; min-height: 100%; }
#wrapper { margin: 0 auto; oveflow: hidden; width: 960px; // width optional }
#left { background: yellow; float: left; width: 360px; // width optional but recommended }
#right { background: grey; margin-left: 360px; // must agree with previous width }
</style>
</head>
<body>
<div id="wrapper">
<div id="left">
Left
</div>
<div id="right">
</div>
</body>
</html>
There are many variations on this depending on which columns need to be fixed and which are liquid. You can do this with absolute positioning too but I've generally found better results (particularly in terms of cross-browser) using floats instead.