DRIVECRYPT securely and easily protects all proprietary data
on notebooks and desktop computers 100% of the time without
users having to think about security. Any organization, from
a small company to a large international firm with thousands
of users in the field, can effectively protect business
plans, client lists, product specifications, confidential
corporate memos, stock information, and much more with this
disk encryption product.

How DriveCrypt`s On-the-fly Encryption Works

As data is read from the hard disk, DRIVECRYPT automatically
decrypts the data before it is loaded into memory. When data
is written back to the hard disk, it is automatically
re-encrypted. The disk encryption/ decryption process is
completely transparent to the user or any application
program -the data is caught on the fly as it transfers
back and forth between the hard disk and memory.
Consequently, users dont need to remember to decrypt or
re-encrypt their data, or change the normal operation of the
PC. In addition, only individual files are decrypted at any
one time, not the whole hard disk.

http://www.securstar.com