I find that I can use OpenOffice Draw in multiple instances, switching between them with alt-tab. Or I could use Draw to look at one presentation and Microsoft Powerpoint to edit another.
But even Microsofts own free Powerpoint-viewer (to view a presentation) runs parallel with Powerpoint (to edit another presentation). You can download it from download.microsoft.com.
The only thing that doesn't work with my MS Powerpoint 2000 is using that program for two presentations at the same time. But with the 3 above alternatives, who cares?
Hope this helps.
What type of software will allow me to diplay a presentation and also work on womething else at the same time? I have one computer but 2 screens.