Here ya go. This works fine in FireFox
<head>
<style type="text/css">
<!--
.notopborder {
border-top-style: none;
border-right-style: solid;
border-bottom-style: solid;
border-left-style: solid;
color: #000000;
}
-->
</style>
</head>
<body>
<table cellpadding="0" cellspacing="0" width="500" class="notopborder" >
<tr>
<td>Column 1</td>
<td>Column 2</td>
</tr>
</table>