Well I'm not looking to encrypt my files, just restrict login.
If you're just talking about AD/Windows authentication and want to go past username and password, you can look into two-factor authentication... smartcard/usb-token and PIN.
If your AD password is secure, then logins on your system are secure. If not, change your password.
I honestly can't think of a reason why you would want/need a secondary login requirement unless you're afraid that a domain admin might log in and find something you don't want them to see. If that's the case, stop doing whatever it is you are doing that is against company policy.
Can you give me some info on how to set this up, I'm assuming this would function kind of like a usb key right?