Thunderbird Upgrade - Should I?

[Graham Watkins]

Hi all,

I'm getting a nagging message on Thunderbird telling me to upgrade to 
the latest version as the one I'm using will soon no longer be 
supported.  I've downloaded the tarball for 11.01 from Mozilla but I am 
filled with foreboding. Is it safe to install this over the top of my 
existing Thunderbird installation or am I likely to trash something 
and/or lose all my mail?

Might it be safer to leave things alone until I decide to upgrade my 
entire system?  I'm using Ubuntu 10.4.

Cheers,

Graham