Hibernate novamente

ainda sobre hibernate, criei essa classe `para gerar as tabelas,

package koop.app.transacao;

import koop.app.entity.*;

import org.hibernate.cfg.AnnotationConfiguration;

import org.hibernate.tool.hbm2ddl.SchemaExport;

public class GeraTabelas {

public static void main(String[] args) {
    AnnotationConfiguration cfg = new AnnotationConfiguration();
    cfg.configure();
    cfg.addAnnotatedClass(Pessoa.class);
    cfg.addAnnotatedClass(Cliente.class);
    cfg.addAnnotatedClass(Funcionario.class);
    cfg.addAnnotatedClass(Produto.class);
    cfg.addAnnotatedClass(CategoriaProduto.class);
    SchemaExport se = new SchemaExport(cfg);
    se.create(true, true);

}

}

e aqui o hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>

net.sf.hibernate.dialect.PostgreSQLDialect postgres 123456 jdbc:postgresql://localhost/Koop org.postgresql.Driver true true yes 'Y', no 'N' net.sf.hibernate.transaction.JDBCTransactionFactory false

quando executo da esse erro:

<blockquote>

Exception in thread “main” org.hibernate.HibernateException: Dialect class not found: net.sf.hibernate.dialect.PostgreSQLDialect

at org.hibernate.dialect.Dialect.instantiateDialect(Dialect.java:239)

at org.hibernate.dialect.Dialect.getDialect(Dialect.java:228)

at org.hibernate.tool.hbm2ddl.SchemaExport.(SchemaExport.java:86)

at org.hibernate.tool.hbm2ddl.SchemaExport.(SchemaExport.java:61)

at koop.app.transacao.GeraTabelas.main(GeraTabelas.java:17)</blockquote>