<?php $i=1; ?>
<?php while($sonuc4=mysql_fetch_array($query4)){
if($i<=5){?>
<ul class="blog column column_1_2">
<li class="post">
//içerik
</li>
<?php
}
if($i==5)echo '</ul><ul class="blog column column_1_2">';
if($i>5){ ?>
<li class="post">
//içerik
</li>
<?php } ?>
<?php $i++; } ?>
</ul>