I would have gone with display:inline-block for generic side-by-side display but you're trying to do a horizontal nav. I wouldn't use the table cell display as it's quirky and you'll end up having to clean up other bugs.
html:
<ul id="navigation">
<li ><a href="/some-link.html">Some link</a></li>
<li ><a href="/some-link2.html">Some link 2</a></li>
<li ><a href="/some-link3.html">Some link three</a></li>
</ul>
css:
#navigation{
width:550px;
margin:0;
padding:0;
list-style-type:none;
overflow:hidden;
}
#navigation li{
float:left;
}
#navigation li a,#navigation li a:hover{
display:block;
padding:4px 21px 4px 20px;
text-decoration:none;
}