It's much more security for the same amount of effort, and actually BitLocker is designed to allow you to have encryption without a user-supplied password at all because the TPM stores the key (although you still need to retain the Recovery Key for certain atypical scenarios, and you can optionally still require a user-supplied PIN as well).

In terms of a little safer rather than NSA-proof, if you're going to have your users typing in passwords anyway, I don't see why you wouldn't want to use proper disk encryption. And that's interesting, I didn't realize Dell systems cached a copy of the HDD password in some form in order to enable that functionality. Thanks to your post I took the time to try using the admin's password right in place of the HDD's password, even though they're clearly different, and it worked like a charm, who would have thought? The text on that admin's password page goes: 'Also, the admin password can be used to delete the HDD password.', it just doesn't tell you how: It's just a matter of typing the admin's password where you should type HDD's password. What you don't get it is that the BIOS itself keeps a copy of HDD password on it, but even if you reverse engineer it you won't be able to extract it because that copy of the (HDD) password was scrambled/encrypted by the admin's (BIOS) password, so as long as you know admin's password you can extract the plaintext of the HDD's password as long as the HDD was kept on the same machine that used to set its password all along. (We're considering whether or not to employ truecrypt or bitlocker over the machines or not, 'til then we're using HDD's passwords.)

The HDD is really not encrypted at all, we just want to make it a bit safer, not NSA-proof. The HDD password is kept on disk, but unaccessible for ordinary users, if the password was kept on the HDD controller (the disk-side part of it) a simple HDD controller switcheroo would solve the problem. You're wrong in many ways, the ATA specification do have a specific command for that since ages ago.

Password protected harddrive