Boas...
Eu costumo fazer algo do género:
#menu ul{
list-style:none;
}
#menu{
margin: 0 auto;
background:#000;
border-bottom: 4px solid #006699;
display:table;
width: 900px;
height: 35px;
padding-left: 100px;
}
#menu ul li{
display:inline;
}
#menu ul li a{
font-family:"Trebuchet MS", Arial, Verdana;
font-size:20px;
color:#FFFFFF;
text-decoration: none;
float: left;
padding: 5px 20px;
}
Espero que ajude!!