I have tried the following in Eclipse:
File / New / Other / JBoss-IDE / J2EE-Products / J2EE 1.3 or 1.4 Project
The following problem occurs:
The selected wizard could not be started.
Reason:
org.eclipse.jdt.internal.ui.wizards.NewWizardMessages.getString(Ljava/lang/String;)Ljava/lang/String;

And I have tried the following:
Window / Preferences / JBoss-IDE / Deployer
The following problem occurs:
Unable to create the selected preference page.
Reason:
Plug-in org.jboss.ide.eclipse.deployer.ui was unable to load class org.jboss.ide.eclipse.deployer.ui.preferences.MainPreferencePage.

This problems occurs with JBoss IDE 1.4.1 and JBoss IDE 1.5.

Is there any possibility to run Eclipse 3.1 with a JBoss IDE ?