Java plugins for firefox

[Paul]

Hi there,

I am trying to look at the nasa countdown clock at
http://countdown.ksc.nasa.gov/shuttle/countdown/cdt/

however I get a popup panel which says I need to INSTALL MISSING PLUGINS:::

I follow the instructions biut it fails and gives me your e-mail for 
problems.

I have :

Linux Mint 6, Ubuntu 8.10, firefox 3.0.14

preferences has java enabled, and I have even tried to install he Sun 
java 6 bin files.
All to no avail.

Please help

Paul

THNX