Live Preview first made its debut in PowerPoint 2007, and continues being available in PowerPoint 2010 as well. Unfortunately, PowerPoint 2007 had no Live Previews for Chart Styles and that ability is not made available in PowerPoint 2010. Live Preview allows you to see/preview how an actual change will look on the slide before you decide to accept or decline that change.
Learn more about Live Preview in PowerPoint 2010 for Windows.

