found this from google:
Configuring this PowerPoint feature is simple. 1. Start PowerPoint on the primary monitor and open the required slide show.
2. Choose Slide Show – Set up Show menu. (I have used Office 2003 as a reference).
3. Notice that there is a section called Multiple Monitors.
4. This is enabled only when dual monitors are configured.
5. Open the popup – “Display slide show on” popup and choose ‘Secondary Display’.
6. Also enable the Presenter View.
7. That’s it. Now run the presentation as usual.
8. The secondary display will show the presentation in full screen mode.
9. You will also see a Presenter view on your base monitor. From this view, you can read notes, navigate slides, view slide thumbnails, view elapsed time and so on.