WinDefender provides you with a service to keep your
valuable files encrypted on your hard drive. When you
want to use them you enter the password and then
WinDefender will automatically (on-the-fly) decrypt them
when reading from the hard drive (floppies, cd-rom, etc.)
and encrypt them when writing to. This will occur
absolutely transparently for you - WinDefender uses a
special low-level driver which can work fine with any file.