TrueCrypt is a software system for establishing and maintaining an on-the-fly-encrypted drive. On-the-fly encryption means that data are automatically encrypted or decrypted right before they are loaded or saved, without any user intervention. No data stored on an encrypted volume can be read (decrypted) without using the correct password or correct…
I have been using TrueCrypt for over a year on my laptop. I keep my QuickBooks and other sensitive files in it. My assumption has always been that if my laptop is stolen that my XP login password would be cracked pretty easily. Ophcrack showed me how easy it can be done. My other assumption is that breaking into TrueCrypt would be way too hard for most thieves. I highly recommend TrueCrypt.