The most important information to transfer over are your keys. You can do this in two ways:
1. Simply copy the public and private keyring files (pubring.pkr, secring.skr) from one machine to the other. This is the simplest way.
2. Export all the keys you care about ("pgp --export" for the public keys, and "pgp --export-key-pair" for your private keys). After you import them, you'll need to re-set the trust of your key pairs.
If you have edited your preferences file PGPprefs.xml, you can copy that over as well, but you will likely need to re-edit it to account for file path changes. It's probably easier to make any edits again in your new preferences file.
Regards,