I have used
JBoss before for an EJB container. As far as a J2EE sdk, the standard OSX install should have it included. You probably could update to
java 1.4.1 as well using software update. Just a heads up, though - swing apps do NOT work under osx java 1.4.1
You will have to upgrade to panther(10.3) to get java 1.4.2 to get swing apps to work(Or you can use the java 1.3.1 jdk on the os if that meets your needs)
good luck!
mark