Okay, perhaps I am the LAST person who uses PowerPoint on a regular basis to know that there has been a Presenter's View built-in to the software for the last couple of versions...both on the PC and the Apple versions. This mode allows you to set-up your laptop (or a desktop with two video cards) to show the presentation on the monitor the audience can see, while it allows you, the presenter, to see your notes view as well as small thumbnails of the slides, and it includes a few other useful options, too. Simply type "presenter" in the PowerPoint help file and there are well-done directions for setting up the dual monitors and the views. I am so happy I don't have to drag my paper notes with me anymore for presenting!
Two tips...the iBook does not have the ability to do anything but mirror the laptop monitor (unless you install an update which I actually did successfully on my brand new 12" iBook after taking a big breath), so I do not believe you can use the presenter's view. And, on my Windows XP laptop, I could not have the mirroring turned on (function-F10) when I was trying to get the presenter's view to work on dual monitors.
Just in case anyone else did not know about this!