Truecrypt is the best. Axcrypt is very good and easier to setup. Download from cnet
Not email but... Dropbox on-line storage gives you 2GB free. Encrypt a file and drop it in your dropbox folder. Then send a link to the recipient and they download.
Google 'How to use Dropbox' for more details. It's a useful app anyway, even if you want to stick to posting mem sticks.