No suitable driver found

Greetings,

I've been looking for a solution to this error for a few days now.
Everything I've found says that the problem should be that I have a
malformed url but I've gone over it dozens of times and I don't think
that it's wrong (I wish it was). I'm trying to use hibernate tools to
generate my database schema through the JDBC driver. Hibernate is pretty
good at this. I've done it many times before in other databases (MySQL,
MsSQL, Oracle, HSQLDB, etc...). I'm using,

PostgreSQL server version 8.3.7 that I installed through the
http://yum.pgsqlrpms.org/8.3/redhat yum repository.
I'm using version 8.3-603.jdbc4 of the jdbc driver (I've tried several
others including the 8.3-605 and the 8.4-701 all with the same error)
I'm using JDK 1.6.0_13 (with 1.5 source/compile targets)

I'm able to log into the database

I'm getting the following stack trace,
11:09:45,533 INFO org.hibernate.tool.hbm2ddl.SchemaExport - Running
hbm2ddl schema export
11:09:45,535 INFO org.hibernate.tool.hbm2ddl.SchemaExport - exporting
generated schema to database
11:09:45,538 INFO
org.hibernate.connection.DriverManagerConnectionProvider - Using
Hibernate built-in connection pool (not for production use!)
11:09:45,538 INFO
org.hibernate.connection.DriverManagerConnectionProvider - Hibernate
connection pool size: 20
11:09:45,538 INFO
org.hibernate.connection.DriverManagerConnectionProvider - autocommit
mode: false
11:09:45,540 INFO
org.hibernate.connection.DriverManagerConnectionProvider - using driver:
org.postgresql.Driver at URL: jdbc:postgresql://localhost:5432/mydatabase
11:09:45,540 INFO
org.hibernate.connection.DriverManagerConnectionProvider - connection
properties: {user=myusername, password=****}
11:09:45,555 ERROR org.hibernate.tool.hbm2ddl.SchemaExport - schema
export unsuccessful
java.sql.SQLException: No suitable driver found for
jdbc:postgresql://localhost:5432/mydatabase
at java.sql.DriverManager.getConnection(DriverManager.java:602)
at java.sql.DriverManager.getConnection(DriverManager.java:154)
at
org.hibernate.connection.DriverManagerConnectionProvider.getConnection(DriverManagerConnectionProvider.java:133)
at
org.hibernate.tool.hbm2ddl.ManagedProviderConnectionHelper.prepare(ManagedProviderConnectionHelper.java:52)
at
org.hibernate.tool.hbm2ddl.SchemaExport.execute(SchemaExport.java:252)
at org.hibernate.tool.hbm2ddl.SchemaExport.create(SchemaExport.java:211)
at
org.codehaus.mojo.hibernate3.exporter.Hbm2DDLExporterMojo.doExecute(Hbm2DDLExporterMojo.java:112)
at
org.codehaus.mojo.hibernate3.HibernateExporterMojo.execute(HibernateExporterMojo.java:152)
at
org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:579)
at
org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:498)
at
org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegmentForProject(DefaultLifecycleExecutor.java:265)
at
org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:191)
at
org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:149)
at
org.apache.maven.DefaultMaven.execute_aroundBody0(DefaultMaven.java:223)
at
org.apache.maven.DefaultMaven.execute_aroundBody1$advice(DefaultMaven.java:304)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:1)
at
org.apache.maven.embedder.MavenEmbedder.execute_aroundBody2(MavenEmbedder.java:904)
at
org.apache.maven.embedder.MavenEmbedder.execute_aroundBody3$advice(MavenEmbedder.java:304)
at org.apache.maven.embedder.MavenEmbedder.execute(MavenEmbedder.java:1)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:176)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:63)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at
org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
at
org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
at
org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:408)
at
org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:351)
at org.codehaus.classworlds.Launcher.main(Launcher.java:31)

Any help would be greatly appreciated.
Cheers!
John