Problemas de visualização FF e IE

[Dav7]

o truque do espaço não resultou, aqui vai o codigo:

CSS:

Código:

/* Menu Imagens
----------------------------------------------- */
#menu-items ul li{
display: inline;
font-weight: bold;
list-style-type: none;
padding: 5px 20px 5px 0;
margin: 0;
}
#menu-items li span.home{
background: url('http://4.bp.blogspot.com/_7XLk5hM-lpg/SWuQeWD1jII/AAAAAAAAAvs/D7DUokaa3vE/s320/home.png') no-repeat;
padding: 0 0 0 20px;
}
#menu-items li span.about{
background: url('http://2.bp.blogspot.com/_7XLk5hM-lpg/SWuRPQufR5I/AAAAAAAAAv8/bnFZ_gXnb3U/s320/sobre.png') no-repeat;
padding: 0 0 0 20px;
}
#menu-items li span.contact{
background: url('http://4.bp.blogspot.com/_7XLk5hM-lpg/SWuMN4x7boI/AAAAAAAAAu0/GWurQ1xcCn0/s320/email.png') no-repeat;
padding: 0 0 0 20px;
}
#menu-items li span.english{
background: url('http://1.bp.blogspot.com/_7XLk5hM-lpg/SWuRZzuQ6ZI/AAAAAAAAAwE/avNv-XCXCHg/s320/ingles.png') no-repeat;
padding: 0 0 0 20px;
}

HTML:

Código:

<div id="menu-items">
<ul>
<li><center><span class="english"><a href="http://www.buxmaking.com/">English</a></span></center></li>
<li><center><span class="contact"><a href="http://www.ganha-facil.com/2008/06/contacto_6452.html">Contacto</a></span></center></li>
<li><center><span class="about"><a href="http://www.ganha-facil.com/2008/03/ganha-dinheiro-na-net.html">Sobre</a></span></center></li>
<li><center><span class="home"><a href="http://www.ganha-facil.com/">Início</a></span></center></li>
</ul>
</div>