Apple have introduced accessibility options into almost all of their devices and operating system in recent releases. The RNIB website explains how to get the most from these settings. Visit Apple Accessibility on RNIB (external link).
Mac OS X has an in-built screen reader called Voiceover.
Windows also has a good screen reader built into Windows 8, Narrator. This is also available on earlier versions of Windows, but there are better open source alternatives (See Software – Screen Readers – NVDA and Thunder).
Windows also allows customisation of the theme or display settings from within the Control Panel area. Here you can adjust the colour contrast to particular colour schemes or customise to your exact requirements. Also, the mouse settings will allow for adjustments to the size and colour of the mouse pointer, whether you require trails or a locator to detect the position of the pointer. You can also download free galleries of mouse pointers (see resources).