Dual display output is a lot of benefits, take the demonstration PowerPoint courseware as an example, you can control the playback on the main display, while on the secondary display (projector side) output demo (such as figure). To achieve such a function, a dual-head video card is often required. In fact, if you use PowerPoint 2007, you can also easily achieve dual display output capabilities.
Run PowerPoint 2007, switch to the Slide Show tab, set the display on which monitor the presentation is displayed in the presentation location, and resolution to show the resolution used by the presentation. Note that the set resolution (refresh rate) cannot be greater than the maximum resolution (or refresh rate) supported by the projector. Then, before using Presenter view, click Start from scratch to play the presentation. In this way you can control the playback progress and rhythm in the host, enlarge the display of notes text as a presenter of the content, etc., very convenient.