Here is a suggested structure for your specific case:
HTML
<ul>
<li><a href="#">Link1</a>
<ul>
<li><a href="USEPCreate.html">Link1a</a></li>
<li><a href="USEPUpdate.html">Link1b</a></li>
<li><a href="USEPRecovery.html">Link1c</a></li>
</ul>
</li>
<li><a href="#">Link2</a>
<ul>
<li><a href="USEPCreate.html">Link2a</a></li>
<li><a href="USEPUpdate.html">Link2b</a></li>
<li><a href="USEPRecovery.html">Link2c</a></li>
</ul>
</li>
</ul>
CSS
ul > li { width:100px; float:left; }
ul > li > ul { display:none; }
ul > li:hover > ul { display:block; }
ul > li > ul { padding-left:10px; }
View the code on http://jsfiddle.net/ChvjL/10/