I would have expected Eclipse to start OC4J with the right host/port combination, so try to start back at the beginning using the original link I posted by deleting the OC4J server instance and following these steps again.
http://www.eclipse.org/webtools/community/tutorials/OracleServerAdapter/OracleServerAdapter.htmlI would focus in on setting of:
JAVA_HOME: Directory where J2SE was installed
ORACLE_HOME: Directory where oc4j_extended_101300.zip was extracted.
Hope that helps.