make this css menu into an drop down

[char]

hi there guys how would i make this simple css menu into an drop down

<div id="menu">

<a title="Home" href="index.php" class="nav">Home</a>
<a title="WebHosting" href="#" class="nav">one</a>
<a title="Website Design" href="#" class="nav">tow</a>
<a title="Other Services" href="se#" class="nav">Drop down here</a>
<a title="Ecommerce" href="s#" class="nav">three</a>
<a title="CMS" href="#" class="nav">Four</a>
<a title="Contact us" href="contact_us.php" class="nav">Contact us</a>
</div>

css code

#menu {
height:30px;
line-height:30px;
background-color:#FFF;
color:#000;
}
#menu ul {
list-style-type: none;
padding-left: 20px;
}
#menu ul li {
display: block;
float:left;
}
#menu ul li a {
padding: 0 20px 0 0;
text-decoration: none;
font-weight: 100;
font-size: 14px;
color:#000;
}
#menu ul li a:hover {
	color:#000;
	text-decoration: none;
	text-align: center;
}
a.nav, a.nav:link, a.nav:visited {display:block; width:135px; height:25px; background:#4683B0; border:1px solid #000;margin-top:0px;text-align:center; text-decoration:none; font-family:verdana, arial, sans-serif; font-size:12px; color:#FFF; line-height:25px; overflow:hidden; float:left;}
a.nav:hover {color:#fff; background:#4683B0;}
a.nav:active {color:#fff; background:#4683B0;}

thank you again i would like to make this an drop down as it fits really nicely with the rest off my website

cheers

[SB65]

Have a look here for a good tutorial.