[Victor D]

Yes, it makes all items looks like them have equal height and the layout is more accurate.
I can't post complete solution since the whole products_t.tpl significally differs from original but here's some clues

        {foreach from=$row item=product name=cycle}
          {if $product}
            <td class="product-cell product-cell-buynow"  style="border:1px solid #ccc;border-top:0px none;">
<img height="1" width="172" src="{$ImagesDir}/m21.gif" alt="" /> 
                {if $config.Appearance.buynow_button_enabled eq "Y"}
                  {include file="customer/main/buy_now.tpl"}
                {else}
                  &nbsp;
                {/if}

            </td>
{if not $smarty.foreach.cycle.last}<td><img src="{$ImagesDir}/spacer.gif" height="5" width="5" alt="" /></td>{/if}

          {/if}
        {/foreach}
      </tr>
      
      {if not $smarty.foreach.products_matrix.last}<tr><td colspan="{$config.Appearance.products_per_row*2-1}"><img src="{$ImagesDir}/spacer.gif" height="5" width="5" alt="" /></td></tr>{/if}

    {/foreach}