Encryption

Sometimes there are things you'd just rather keep to yourself. Windows has encryption functionality built into the file system, but it's a) not very robust and b) a proprietary part of the NTFS file system. I prefer the TrueCrypt Foundation's TrueCrypt, a free and open-source encryption system that can create encrypted volumes out of a file on disk or a physical drive (such as a USB drive).

Most of the program's functions (like creating encrypted volumes) are wizard-driven and easy to use, even if you know nothing about encryption. The encryption algorithms it uses are fully documented industry standards, such as Triple DES and Blowfish, so the encryption itself is not going to be a weakness. You can even set up a USB thumb drive or an external hard drive with its own copy of TrueCrypt if you want to take your encrypted files with you to a machine that doesn't have TrueCrypt installed. (Note that you'll need administrative access on the target computer for this to work.)