<?php
//veritabanı bilgilerinide ekle.
$yansiraaa=0; 
$sorbakalim=mysql_query("select * from tablo");
?>
<table>
<tr>
<?php while($yazbakalim=mysql_fetch_array($sorbakalim)){ ?>
 <td><table width="25%" border="0" align="left">
      <tr>
        <td colspan="2" bgcolor="<?=$tableborder?>" align="center" class="baslik_beyaz21"><a href="urungoster.php?id=<?=$id?>">
          <?=$markaadi?>
          <?=$urunadi?>
        </a> <img src="img/yeni.gif" alt="yeni" width="50" height="12" /></td>
      </tr>
      <tr>
        <td width="50%" class="mansetresim"><img src="Upload/galeri/<?=$resim?>"/></td>
        <td width="50%" class="yazi_min"><?=$tanitim?></td>
      </tr>
    </table></td>
<? 
$yansiraaa++; 
if($yansiraaa % 2 == 0){ 
echo "</tr><tr>"; 
} 
} 
?> 
</tr>
</table>

Bu sefer olması gerekiyo ama