This is why solutions like Bitlocker with a good TPM or FileVault are so important.<p>They can essentially guarantee that the disk encryption key will only be released from the security module if the computer is running a fully-trusted and signed OS. Even if you take the drive out of the machine, the data on that drive is completely useless to you.<p>Incidentally, this is also what makes short PINs secure; the TPM contents are unreadable, even to a skilled attacker, so if the TPM is guaranteeed to wipe itself after 10 tries, even a 4-digit PIN is secure enough.