/components/com_virtuemart/themes/default/templates/common/relatedProducts.tpl.php

<table width="100%" align="center">
<tr>
<?php $relItemNo = 0; ?>
<?php
while( $products->next_record() ) {
if ($relItem == 3) {
echo "</tr>\n<tr>";
$relItem = 0;
}
?> 
<td width="33%" valign="top">
<?php echo $ps_product->product_snapshot( $products->f('product_sku') ) ?>
<br/><br/><br/>
</td>
<?php $relItem++;
}
?>
</tr>
</table>