I would highly recommend you use TrueCrypt. It is open source, peer reviewed and uses widely accepted, peer reviewed, encryption algorithms.
It has matured quite a bit in the last year or so and offers a number of different options.
And no, I am not in any way connected with them. http://www.truecrypt.org/downloads.php
Securing a notebook to prevent physical access is as close to impossible as anything I can think of. To think you can secure a plastic case with special screws.... well good luck with that! I'll give you a hint. Soldering iron and needle nose pliers. Put it back together with a bigger screw. Even a 10 year old can figure that one out.
The bottom line is that there is no way to secure any computer data if one has physical access to the equipment, except with encryption. Cryptography is the only protection your data has. Anything else is something to sell to the uninformed that will make them feel good.