1) The book - Web Services Up and Running by Martin Kalin.
2) Enthuware tests by Fritz Walveran.
3) OCEWSD study guide by Mikalai Zaikin.
4) Designing Web services with J2EE 1.4 platform : JAX-RPC, SOAP, and XML technologies (For best Practices)
I did not have any prior experience in Web Services and prepared for about 5 months.
A point worth mentioning - The exam had couple questions to closely test understanding of how access control (authorization,authentication) works when EJB is deployed as web service and the role of web container and the ejb container there.
I will also share some useful web site links which helped me get a clearer understanding of some topics in ths exam.