I started to get a tad paraniod the other day (those of you who know me are probably laughing your buttholes off, but thats ok. Annnyway, i decided to implement GPG into my email so i could send stuff to and from work without having prying eyes. Thunderbird was quite easy to implement and works VERY well, all the details and the plugin for thunderbird can be found at http://enigmail.mozdev.org/
Unfortunately at home, i have to use outlook, most people would normally have to deal with it the other way around, but at work we use Thunderbird and at home I need to use Outlook so that i can sync appointments, etc. with my PDA. All the details on how to go about setting up GPG for use with outlook is available at http://www.gpg4win.org/.