http://www.microsoft.com/technet/sysinternals/utilities/zoomit.mspx
One of my colleagues was looking for the MS mouse software. When probed he mentioned that the zoom utility that is provided with MS mouse is a neat one, where you can control the zoomed area. Quite useful when you’d want the audience to focus on a specific area on the screen. I was running Vista at the moment and I found that the Magnifier tool in Vista was quite nifty in this regard. The magnifier can be found under Accessibility (Shortcut: ΓΏ + u)
Since Win2K3 and XP doesn’t have the same magnifier, for those OSs you could use Zoomit.
