Have you places the jar file containing the JDBC driver in the lib folder of the configuration that you are using?
The error indicates that the driver class can not be found.
yes I have them copied to .../default/lib
where is the postgre jar file ? it can go in the lib directory in jboss with all the other jars , it will then find it.
i got it working :-) it is in lib under the default directory though to answer your question.