By creating a user account and password, you automatically enable an initial layer of security on your Mac. If you want to be extra cautious, consider using encryption: When you encrypt your drive, you essentially make it impossible to read for those without the means to decrypt it.
Apple latest Mac operating system, OS X 10.7 Lion includes FileVault 2, the latest version of Apple’s method of file protection. FileVault 2 is designed to encrypt your hard drive. As long as your files are saved to the internal drive, they’ll be safe.
In this how-to, we’ll go through the steps on activating FileVault 2 for your Mac’s internal startup drive.