One-column three-column?

I’m designing a wordpress page for a campaign and it should look like this in the end:
https://img.idioti.nu/images/example.png

I used this to get three columns

<div id="content" class="narrowcolumn" role="main">

<table cellpadding="10" cellspacing="10" border="0">
<?php
$col = 0;
$cols_per_row = 2;
while (have_posts()) : the_post();
  if($col == 0) echo '<tr>';
  ?>
  <td class="column'<?php echo $col; ?>" style="vertical-align: top">
  <div class="post" id="post-'<?php the_ID(); ?>'">
	<h1><a href="<?php the_permalink(); ?>" rel="bookmark" title="<?php the_title(); ?>"><?php the_title(); ?></a></h1>
	<div class="descr"><?php the_time('l, F jS Y, G:i a T'); ?></div>
	<div class="entry">
	  <?php the_content('Read the rest of this entry ?'); ?>
	</div>
  </div>
  <td>
  <?php
  if($col++ >= $cols_per_row){
	$col = 0;
	echo '</tr>';
  }
endwhile;
?>
</table>

My problem now is to put in the one-column post at the top. How do I do that?