How to install Jboss 4 in open source – ubuntu operating system

I’m using ubuntu version 6.06 and I want to install Jboss 4. I downloaded jboss installer file jboss-4.0.4.GA-Patch1-installer.jar. Installed Java 5.
Made following changes in my .bashrc file:-

export JAVA_HOME=/usr/lib/j2sdk1.5-sun
export JAVACMD=${JAVA_HOME}/bin/java
export PATH=${JAVA_HOME}/bin:/usr/bin/:${PATH}

I then executed the following comand:
java -jar jboss-4.0.4.GA-Patch1-installer.jar

Running this from ordinary user terminal returns the following message: Invalid or corrupt jarfile jboss-4.0.4.GA-Patch1-installer.jar ;

Running this from user root returns the following:Failed to load Main-Class manifest attribute from jboss-4.0.4.GA-Patch1-installer.jar

What is it that I need to do?

Regards