Interesting paper found via USB Hacks: Hacking Password Protected Laptops.
That’s right: It’s easy to protect your laptop with a password (at BIOS or OS level). But if your laptop is stolen, your data are unsafe! It’s very easy to bypass or recover your passwords and access your data as usual.
To increase your data privacy, your have to encrypt them! Using Truecrypt for example. And for even more security, don’t put your laptop in standby! Passwords can even be recovered by bringing your laptop at very low temperature!