The present invention provides methods and apparatuses for computer system security. According to certain aspects, embodiments of the invention comprise a portable storage device that, when attached, “unlocks” a computer system, such as a desktop, laptop, tablet computer running a conventional operating system such as Windows, thereby creating added security. More particularly, embodiments of the invention use a standard USB memory stick as an “ignition key” to unlock and operate a PC, tablet or other computer system. The ignition key can be required to boot the computer, utilize peripheral devices, ports, network connections, a keyboard and/or a mouse of the computer system, and limit access to certain parts of computer. According to further aspects, in these and other embodiments, the invention is implemented using a modified BIOS that prevents a computer from fully booting into an operational state until verifying the presence of, and information stored on the “ignition key” connected to the computer.