The primary operating system of a computer such as a notebook computer is stored on disk in a hard disk drive and a smaller, secondary operating system such as an email operating system, wireless phone operating system, DVD player operating system, etc. is stored on disk and is transferred to flash memory within the HDD upon power-down of the primary operating system. In this way, should the user subsequently elect to power up the computer only for a limited secondary purpose, the user can elect to boot the associated secondary operating system from flash memory of the HDD without having to spin up the disks, saving energy and reducing boot time.