> Well - I can't get this to work under linux&firefox (just get an download
> window), ....

Do you get the download screen from java web start, or is it a generic one from your browser? If it's the latter, do you have java web start (java 1.4 or higher) installed?

Does the java web start log say anything useful (open java web start application manager, file->preferences->advanced, tick 'log output')?
Thanks for testing :-)