Try this;
At the top of each top, set a variable
$current_page = 'id'; //id being whatever you use for the page id's
Then when you print out your links, you can check for
echo '| ';
while ($row_result_SubNav = mysql_fetch_assoc($result_SubNav))
{
if($row_result_SubNav['id']==$current_page)
{
echo $row_result_SubNav['name'] . ' | ';
} else
{
echo "<a href=\"about.php?subID=$row_result_SubNav[id]\">$row_result_SubNav[name]</a> | ";
}
}