First off just so you know, there is no need to do PortableRemoteObject with JBoss (though doing so may help your portability to inferior appservers or if you think you may really actually use corba).
Each call on a STATELESS sesion bean will go to a different instance from the pool (per spec). There is absolutely no need to call to home.create for each call (and doing so has negative characteristics if you do clustering later).
STATEFUL session beans throw an exception if you try and make concurrent calls on the same instance.
moreover if you're doing a new app you may want to investigate jboss's ejb3 container as it uses jboss serialization/remoting by default which is much lighter weight in transmission cost.
Thanks for the reply. I will look into ejb3 in the future, for now we will use rmi.