There are many types of hardware that can make computers more accessible. This Braille keyboard is one example of an alternative input device.
People with disabilities will set up their computer in the best way for them. This might include hardware like a screen reader for a person who is blind, or assistive technology devices such as a sip-and-puff system that is controlled by breathing for a person with a motion disability.
There are also a vast number of ways in which people can set up their computer without any additional hardware. This includes software features like high contrast screen display for people with low vision, and SoundSentry which alerts people who are hard of hearing when the computer makes a noise.
Although people can do a lot to make their computers suitable for their needs, you still need to write your document so that the information is accessible. So, remember: If a piece of information could be inaccessible to someone, always convey that information in a second format.
You can get a lot more information about computers and accessibility from Microsoft accessibility Web site. Also, the World Wide Web Consortium has an initiative to make the Internet more accessible. For more information, see World Wide Web Consortium Web site.