High level encryption (with a short out password) could force you to erase the data on the hard disk, or make it unusable, if the computer is stolen, but that would also wipe the data if the user forgot their password. Without high level encryption, just plug in a live disk and you have access to all the data. If you want to secure data, make sure your disk is secure, and don't leave it on the table at your favourite cafe.
The concept that software can protect hardware is nonsense. Once someone has access to your hardware they can wipe your software security programs.