
This article from Tech Republic says that one of the best ways to secure data, whether in storage or in transit, is by using PGP (Pretty Good Privacy) by PGP Corporation. All PGP versions secure email and stored data; the enterprise and desktop editions even encrypt ICQ messages. The enterprise version adds administration tools and a keyserver, which works with Microsoft Exchange, Lotus Notes, and Novel GroupWise servers. The desktop version, useful for SOHO operations, provides the same level of encryption but without the administrator and server applications. The mobile computing version for Palm provides email and disk protection. Windows CE devices get only mail protection.