a.infobox {color:#333333;}
a.infobox:hover { cursor:help; color:#c30; background:white; }
a.infobox span { visibility:hidden; position:absolute; left:50%; width: 200px; margin-top:10; padding:1em; text-decoration:none; }
a.infobox:hover span { visibility:visible; border:1px solid #c30;color:#333333; background:white; }
<!--[if IE 5]>
  a.infobox span { display:none; }
  a.infobox:hover span { display:block; }
<![endif]-->