Gpg4win is a GNU Privacy Guard installer package for Windows 2000,XP,2003 and Vista for EMail and file encryption. Both relevant cryptography standards are supported, OpenPGP and S/MIME (the latter is in progress and currently works with GnuPG2 and Claws Mail).
The following are the software modules included in the Gpg4win software:
GnuPG: The core encryption tool
WinPT: A key manager and helper for various encryption matters
GPA: Another key manager, tasts are simply different
GPGol: A plugin for Microsoft Outlook 2003 (email encryption)
GPGee: A plugin for Microsoft Explorer (file encryption)
Claws Mail: A complete email program including the plugin for GnuPG
You can choose to exclude the optional programs included in the package.