hard drive encryption

[Cerridwyn Llewyellyn <ceridwyn@wolfenet.com>]

What is the best utility freely available for encrypting an entire drive
that won't be used for a length of time?  ie: I'm going away for a period
of time and wish to encrypt the drive while I'm gone, but have no interest
in actually using it while it's encrypted.  I also have no real preference
in what algorithm is used, as long as it's relatively secure.  Speed is 
also not a big consideration, as it will be used once when I leave to encrypt,
and once when i return to decrypt.  
Thanks in advance for the help... 
//cerridwyn//

btw, the OS is Win95 if that matters...