Hente 5 seneste emner fra forum

Hvordan henter jeg de 5 seneste emner i mit forum?
Min forum-side, hvor jeg viser indlæggene ser sådan her ud:
<?php
$sql="SELECT * FROM forum_question ORDER BY id DESC";
$result=mysql_query($sql);
?>
<table border="0" align="center" cellpadding="3" cellspacing="0" bgcolor="#CCCCCC">
  <tr>
    <td style="border: 1px solid #000000; border-top: 0px; text-align: center; width: 25px;"><strong>#</strong></td>
    <td style="border-bottom: 1px solid #000000; border-right: 1px solid #000000; text-align: center; width: 200px;"><strong>Emne</strong></td>
    <td style="border-bottom: 1px solid #000000; border-right: 1px solid #000000; text-align: center; width: 60px;"><strong>Visninger</strong></td>
    <td style="border-bottom: 1px solid #000000; border-right: 1px solid #000000; text-align: center; width: 60px;"><strong>Svar</strong></td>
    <td style="border-bottom: 1px solid #000000; border-right: 1px solid #000000; text-align: center; width: 150px;"><strong>Forfatter</strong></td>
    <td style="border-bottom: 1px solid #000000; border-right: 1px solid #000000; text-align: center; width: 50px;"><strong>Dato</strong></td>
  </tr>
<?php
while($rows=mysql_fetch_array($result))
{
?>
  <tr>
    <td style="border: 1px solid #000000; border-top: 0px; text-align: center;"><? echo $rows['id']; ?></td>
    <td style="border-bottom: 1px solid #000000; border-right: 1px solid #000000; text-align: center;"><a href="index.php?id=18&t=<? echo $rows['id']; ?>"><? echo $rows['topic']; ?></a><BR></td>
    <td style="border-bottom: 1px solid #000000; border-right: 1px solid #000000; text-align: center;"><? echo $rows['view']; ?></td>
    <td style="border-bottom: 1px solid #000000; border-right: 1px solid #000000; text-align: center;"><? echo $rows['reply']; ?></td>
    <td style="border-bottom: 1px solid #000000; border-right: 1px solid #000000; text-align: center;"><? echo $rows['firstname'] . "&nbsp;" . $rows['lastname'] . " (" . $rows['nick'] . ")"; ?></td>
    <td style="border-bottom: 1px solid #000000; border-right: 1px solid #000000; text-align: center;"><? echo $rows['datetime']; ?></td>
  </tr>
<?php
}
mysql_close();
?>
  <tr>
    <td colspan="6" align="right" bgcolor="#E6E6E6"><a href="index.php?id=16"><strong>Opret nyt emne</strong> </a></td>
  </tr>
</table>