Quizas sea una mala idea por la optimizacion:
<select name="select" onChange="location.href=this.value">
<option value="catalogoAdmin1.php">Con stock cero</option>
<option value="catalogoAdmin2.php" selected>Tienen Stock</option>
</select>
catalogoAdmin2.php
---------------------------
<?php
include('conec.php');
conectarse();
$qry=mysql_query("select id,producto,precio,categoria,stock from catalogo where
stock>0 order by id asc");?>
<html>
<head>
<title>Catálogo Administrador</title>
</head>
<body>
<table>
<tr valign="middle" bordercolor="#FFFFFF" bgcolor="#3399CC">
<td align="center" width="5%">Cód.</td>
<td align="center" width="53%">Producto</td>
<td align="center" width="7%">Precio<br>(S/.)</td>
<td align="center" width="5%"><strong>Categ.</strong></td>
</tr>
<?php
while($row=mysql_fetch_assoc($qry)){
?>
<tr>
<td align="center"><?php echo $row['id'] ?></td>
<td><?php echo $row['producto'] ?></td>
<td align="right"><?php echo $row['precio'] ?></td>
<td align="center"><?php echo $row['categoria'] ?></td>
</tr><?php } ?>
</table>
</body>
</html>
y otro archivo similar al catalogoAdmin2.php con la diferencia en:
$qry=mysql_query("select id,producto,precio,categoria,stock from catalogo
where stock=0 order by id asc");?>
Algo asi????