email encryption

After a conversation, about big brother keeping tabs on personal phone conversations and other electronic forms, I asked about how easy it is to setup of email encryption.
After a bit of googling around, I came across the following:

PGP (Pretty Good Privacy) which is a type of encryption software which uses public-key cryptography. The open source version GnuPG (GNU Privacy Guard) seems to be the most widely used version, at least from what I found.
Basically how it works is that it creates a private & a public key. You keep your private key hidden from anyone else. The public key is what you give out to everyone so they can unlock your encrypted emails. There are many different public servers which will house the public keys, that you can search for other people's public keys--so you can receive encrypted emails from them. Other standard ways for sharing your public keys are to place you public key on your website/blog (which seems kind of silly to me) and also to digitally sign your unencrypted emails with your public key included.

I'm using Thunderbird at work (which I've found to be a fairly well made email client, speaking for myself coming from Outlook), which I found a nice plugin, Enigmail, which is a very nice streamlined interface for the GnuPG application.
The process for installing and setting up Enigmail is as easy as setting up an email account. Enigmail has great guide on their website, which should make it easy enough for your mother to set it up.

For those using Gmail, there is also encryption via greasemonkey--read here for more info.

Here are couple more links:
http://lifehacker.com/software/top/how-to-encrypt-your-email-180878.php
http://lifehacker.com/software/email/add-encryption-to-gmail-177061.php