Yes they do work as most of these things encrypt the entire HDD and to access the drive you need to enter the correct Password.
But just like everything it's only as secure as the password is strong. So if you use a Easy Password it's more likely to get broken and then your data is readable.
[i]It does a pre-boot authentication with a password. This seems to be a general deterrent for non-technical users, correct? [/i]
Yes that is correct though it is also a single point of attack by someone who knows what they are doing.
[i]Is this preboot feature important?[/i]
Yes it's important as the entire HDD is encrypted so without it you can not access even the base Operating System.
[i]Datalock encrypts all the data going on the hard drive, so it they can read the drive, they can?t decode the encryption, correct?[/i]
Well sort of here the entire HDD gets Encrypted so if they are unable to boot off the HDD they can not read the data. If they remove the HDD from the computer fit it as a slave the data is still encrypted and to all intents and purposes unreadable.
[i]What encryption level does Datalock use?[/i]
I'm not really sure as it doesn't say on the Zone Alarm Web Site but most of these programs use 256 Bit Encryption.
In addition to the above I should advise that you should not rely on the Password Recovery Provided by Zone Alarm. It may recover your ability at a pinch but it just as easily may not so there is no substitute for Solid, Regular Backup's and you should also backup your Encryption Key and not carry it with the NB.
But be aware that places like Zone Alarm and others of their ilk provide Encryption Breaking Tools to the Authorities to prevent their software being used for anything unwanted by that Government. So if you are into Kiddy Porn Encrypting the HDD isn't going to keep the Authorities out and you out of prison. This type of software will only keep the armatures out of your data and if you where to travel Overseas it's quite possible that you may be required to hand over your Encryption Key so that the Authorities can look at what the computer contains. If you do not comply with this request for the Key they can seize the computer and then at their leisure look at the contents of the HDD.
Other products that you can look at are things like True Crypt
http://www.truecrypt.org/downloads
PPG
http://www.pgp.com/
Win Magic
http://www.winmagic.com/
Safe House
http://www.safehousesoftware.com/
Secure Star
http://www.securstar.com/home.php
Pointsec
http://www.checkpoint.com/products/datasecurity/pc/
All of the above work in a similar manner.
Then there are applications like Prey which can be used to track a stolen NB.
http://www.ilovefreesoftware.com/18/windows/security/prey-free-software-to-track-and-recover-stolen-laptop.html
There are other applications like this but the Pay For services are on a retainer where the Stolen NB phones home and tells mommy where it is along with a Picture from the Web Cam if there is one fitted. You pay to have the Monitoring Site there in case your NB gets stolen.
http://www.laptopcopsoftware.com/?gclid=CKzN3a7suqQCFQRCbgodRl6Axw
They are just a small sample of what is available but they all need to be setup before the NB gets stolen. ;)
Col