A client computer runs an operating system that executes additional applications by loading them using an application loader and executes device drivers for peripheral devices by loading the drivers using a device loader. The operating system restricts the functionality of the operating system, such as by making selected portions and functionality of the operating system unavailable to the user or by limiting the user's ability to add software applications or device drivers to the computer. Additionally, various techniques can be used to remove or reduce the functionality limitations of the computer.