Update!
I am really enjoying Firefox. It can stay on both my Macs. It is well though out and easy to use. A real joy! I will also probably bung it on my partner's iBook sometime over Christmas!
As for the Thunderbird, I gave up.
Also I did add the "oooh" comment about 30 seconds after I wrote the original post, so I am sorry for the confusion! So, Krissel, you are one quick reader!
Fx