Make your mouse cursor larger in Mac OS X.
How to Open the System Preferences in Mac OS X Leopard
An introduction to the Universal Access pane, enable VoiceOver, Zoom, Hearing, Keyboard and Mouse options
Change how the screen moves while you're zooming into it
Enable access for assistive devices
Make your screen flash when an alert appears
Enable sticky keys, allowing some users to use keyboard shortcuts and commands easier
Use the arrow keys on the keyboard to control the mouse
Use slow keys, allowing some users to type without making mistakes
How to zoom into the screen in Leopard.
