Thanks but I've used that tutorial and others to learn how to make the jar file executable and its working if i use "java -jar hello.jar" at the command line.
Unfortunatley i was messing around with the 'open with' command on the jar file trying to fix it and i've made it associated with some html help thing., and i have no idea how to unasociate it.
Anyone know any way i can remove all associations with it?