Example

#nav {
	position: absolute;
	top: 10px;
	left: 10px;
	list-style: none;
	margin: 0;
	padding: 0;
	height: 20px;
	display: inline;
	overflow: hidden;
	width: 201px;
	}
	
#nav li {
	margin: 0; 
	padding: 0;
	display: inline;
	list-style-type: none;
	}

#nav a {
	float: left;
	padding: 20px 0 0 0;
	overflow: hidden;
	height: 0px !important; 
	height /**/:20px; /* for IE5/Win */
	}
	
#nav a:hover {
	background-position: 0 -20px;
	}

#nav a:active, #nav a.selected {
	background-position: 0 -40px;
	}
	
#thome a  {
	width: 40px;
	background: url(images/home.gif) top left no-repeat;
	}

#tguides a  {
	width: 45px;
	background: url(images/guides.gif) top left no-repeat;
	}

#tmag a  {
	width: 62px;
	background: url(images/magazine.gif) top left no-repeat;
	}

#tarchives a  {
	width: 54px;
	background: url(images/archives.gif) top left no-repeat;
	}
-->

<ul id="nav">
  <li id="thome"><a href="#">Home</a></li>
  <li id="tguides"><a href="#" class="selected">Guides</a></li>
  <li id="tmag"><a href="#">Magazine</a></li>
  <li id="tarchives"><a href="#">Archives</a></li>
</ul>

Images

1. home.gif
2. guides.gif
3. magazine.gif
4. archives.gif