JBoss releases with Tomcat V 4.x have the webapps disabled by default. I don't know why and I would like to find out how to get them going. Some posts suggest copying the Tomcat webapp directories (eg ROOT, examples etc) to the JBoss deploy directory (perhaps "default/deploy"), and append ".war" to the end of the directory name. You should then be able to access the web app by (eg) "http://localhost/ROOT/index.jsp" (if Apache is correctly forwarding JSP requests.
Hope this helps.