Late answer but maybe this will help someone else.
It's kind of hard to know what the underlying problem is because it could be a number of things. Still, my bet is that you haven't set the JAVA_HOME environment variable to the path of your java installation. Try doing this (obviously replace /usr/lib/j2sdk1.5-sun with your java installation path):
JAVA_HOME=/usr/lib/j2sdk1.5-sun
export JAVA_HOME
And then try again. Also, there is a binary distribution of JBOSS and you'll save yourself a lot of trouble if you use that instead.
Also, read the JBOSS documentation:
http://www.jboss.com/docs/index
Good luck.