with the greeter example I had exactly the same problem. For me the reason was that my index.jsp file was in WEB-INF. Try to put your index.jsp one level higher, that is directly in the WebContent directory.
Everything that is in the WEB-INF is not directly accessible for a "client" (i.e. the web browser). Therefore the resource "index.jsp" was not available. I advise you to learn more about the structure of web applications in general.