PGP costs too much, and doesn’t work with cool email clients. GPG rocks, but is command line only, which is a pain in the butt for the average user. So I went hunting, and found WinPT, or Windows Privacy Tools.
Succintly, it is a great GUI installer and manager for GPG. It’ll let you generate and manage keys as well as deal with file system encryption. It does everything that I ever used PGP for.
Once it’s installed, then Enigmail for Thunderbird can use it flawlessly. For those who prefer to stay with proprietary email clients (for whatever reason), WinPT comes with Eudora and Outlook plugins.
To sum up, there’s now an excellent, easy, powerful, opensource email encryption setup for windows.