I have always liked having my laptop BIOS boot password on. i.e.  you can't even boot from a CD unless you have first supplied credentials. However I've always been too lazy in the past to login 'twice', once to the BIOS and then to the operating system (OS) as a user. I've got around that as follows:
  1. Make sure that your screen saver is password protected and enabled
  2. Make sure your OS requires a password after resume
  3. Enable automatic user login.
Now you have to supply credentials every time you want to renew access to the machine, but you only have to supply credentials once on boot.
  • This is only useful if the machine is used exclusively  by you
  • You can either use 'sudo' (Linux and OS/X) and 'runas' (MS Windows) or logout/login to run programs as another user.