Privacy and encrypted email servers-which is most effective/useful?

[Your_Moms_Kneepads]

Im and familiar with Hushmail and Ziplip b/c I have accounts with both and use them often. With hushmail you have to send to a hush or elitefitness address. Ziplip you have to use a password for the encryption to take place.
Now, I just took a look at privacyX.com and their system says that you can send encrypted emails to essentially anyone-they just have to send you an email-i guess they can just send you a blank one and that should suffice.
Anyone out there have any critique of these email systems? Also what about PGP. I see places to download it but I have no idea how to use it.