<xsl:for-each select="site/section">
<xsl:if test="position() mod 2 = 1">
<tr align="center" valign="top">
<td width="50%" class="topic_pane">
<xsl:value-of select="@name"/>
</td>
<td width="50%" class="topic_pane">
<xsl:value-of select="following::section/@name"/>
</td>
</tr>
</xsl:if>
</xsl:for-each>