Recently i had a client purchase a new laptop, the only requirement the migration of her thunderbird settings from old to new hardware. Being an outlook user and having not used Thunderbird before i initially scratched my head regarding the matter.
I knew i had to move the mailbox data from one PC to another, after a quick google search around i found that under XP it lives in the C:\documents and settings\username\Application Data\Thunderbird\Profiles\. Copy the folder from this directory to a thumbdrive or some device that you can use to transfer it to the new hardware. I shared a folder and then transferred the data to the UNC path. Once you have all the data onto the new hardware, goto start then run and type: "C:\Program Files\Mozilla Thunderbird\thunderbird.exe" -p ***The path might vary, with differences in operating systems(32/64bit or XP to Vista/7).
Once you run the profile manager, Delete any previous entries if it is a new installation as this will not be required. Click New and follow the prompts. When the wizard requires the path to store the mail files specify the location of the backed up data from the previous system. Once you do this Thunderbird will recognize the previous settings and import them. Finish the wizard and open Thunderbird and test. All should be well.