Recently I had to encrypt some mails using Mozilla Thunderbird 3 in Microsoft Windows, and I wondered if it was possible to import my existing public and private keyrings from Debian into Windows.
Using WinSCP you can securely transfer the .gnupg/pubring.gpg, .gnupg/secring.gpg, .gnupg/trustdb.gpg files from your Linux profile into the %APPDATA%gnupg directory.
Then, given a Thunderbird setup with the Enigmail extension installed, and GnuPG also installed, it’s just a matter of running the Wizard under the “OpenPGP” menu inside Thunderbird.
If you have mail identities already setup, the sec/pub key combination for those identities will be enabled. Then it’s business as usual with Enigmail.