Thunderbird address file

Hello everyone: I'm using Thunderbird on SuSE 9.3. What I would like to do is to save the file containing all of my e-mail addresses to a safe location (probably another hard drive). Then, when needed, I could simply copy and overwrite the 'saved' file with the current file containing the latest e-mail addresses. Also, should I have to re-install Thunderbird, I could retrieve the 'saved' file and simply replace the new (empty) file with my saved copy containing my e-mail addresses. Does anyone know exactly where Thunderbird keeps this e-mail address file? Cheers and thanks, Mike