just build your table and set it so you have a single image in the left side and your thumbnails in the right. so you have your tnails in the right side.
in the left side you can do something like this
<img src='<?php if($_GET['id']){echo "/path/to/images/".$_GET['id'].".jpg";}
else{ echo '/path/to/images/default.jpg';} ?>'>
by the way, javascript has nothing to do with java except the name. javascript, ecmascript, jscript are all pretty similar and generally used for client side scripting.