Dave is looking for a good backup solution for both business and personal. He wants to encrypt the data and back it up. Leo says that if Dave turns on encryption on the drive, that's effective. The OS has encryption: File Vault for the Mac and BitLocker for Windows. He'll have to be sure he backs up the certificate and doesn't lose it. Third party options that work include TrueCrypt.
Leo says that an offsite backup option like Carbonite also encrypts data and only he will have the password.
Disclaimer: Carbonite is a sponsor.