Java Web Server Help

Does anyone use a Java webserver? I have a few questions about using jboss with Tomcat. I downloaded and installed Tomcat separately on my system and it works just fine. However, I can't seem to get the Tomcat bundled with the jboss package to work correctly. I'd appreciate any insight and advice. Thanks.

OK, I have a problem with starting up my Tomcat server. I get no errors when I startup, but I cannot access localhost:8080 and when I try to shut it down, I get this message:

Exception in thread "main" java.lang.NoClassDefFoundError: org/xml/sax/InputSource
at java.lang.Class.newInstance0(Native Method)
at java.lang.Class.newInstance(Class.java:232)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:179)

Does anyone have an idea what went wrong? Please help. Thanks.