Totally trivial with Thunderbird (which includes Enigmail). Now I just need someone to send encrypted messages to.

When it comes to encryption, I prefer to eat my open source style. With their centralized key server and their closed architecture, they could even escrow your keys and you wouldn't know it. In addition, they log records of everyone you communicate with. How's that for cool? Try this: WinPT (http://winpt.sourceforge.net/). It includes plugins for Outlook Express & Eudora, as well as Windows Explorer integration *and* it will install GPG for you, so you don't have to mess with that.