Acca expongo el codigo, gracias de antemano!

<script>// vinculos segun la seleccion del listado
function Send_To()
{
window.location=document.form.lista.value;
}
</script>
<?
$start_lista = mysql_query("select * from table_perfil where idano='".$_SESSION['session_idano']."' order by id_expediente desc")or die (mysql_error());
if($start_lista){
print "<select name='lista' id='lista' onchange='Send_To()'>";
while($list_id = mysql_fetch_assoc($start_lista)){
$selected = "";
if($list_id['id_expediente'] == $_POST['lista']){
$selected = "selected='selected'";
}
print"<option value='registro_tramites.php?visor_tramites_exp=". $list_id['id_expediente']."' $selected>".$list_id['id_expediente']."</option>";
}
print "</select>";
}
?>