If you have important information stored in your machine that you need to protect with the most powerful guardian in the world, TrueCrypt is the application you were looking for.
This software is useful for encrypting the information you need to keep it safe. It uses a sophisticated and new technology that will encrypt under the power of more than 10 different algorithms everything you want.
It allows you to protect your files with a password as well, if you feel they are not hidden well enough. It will help you hide your files in safe places of your hard disk, like partitions.
It comes with a nice and organized interface you will find very accessible.