>>I always assumed that by configuring the port in Eclipse I was not only telling eclipse which port to look for but also which port to configure in the server?
That is an incorrect assumption - you need to change the port both in Eclipse and in JBoss AS (as you found out).
By the way, you since you are using JBoss AS 5.0.1, you should really change the HTTP port in server/xxx/conbf/bootstrap/bindings.xml, not in the server.xml file.
Many thanks,
Jorge