[Hudlug] Java Plugins for Firefox 2

[Derek]

Hi all,
Can anyone help me with the following. I'm running Ubuntu Feisty Fawn
(7.04). Using Firefox 2 browser I've not been able to load a page from
an online bank because it said I did not have Java Runtime Environment
installed. 

Synaptic package manager shows the following file installed:
'java-gcj-compat' ver. 1.0.65-8ubuntu3 which is described as a 'Java
runtime environment using GIJ'.

The Firefox help points to J2RE-1_4_2 which I downloaded as a bin file.
But going onto Mozilla's 'Plugin' site it points to J2RE-6ul which I
also downloaded as a bin.

Question. Is JRE installed? If it is then why the problem?

If it is not, which of the two bin files should I install? 
A further complication to this is that the instructions refer to
changing to the 'plugin' directory for Firefox but I cannot find it.

Any suggestions?

Derek Allen