working with an external monitor

I have vista premium home.
Reason for my question below.
At times, I need to be able to prepare the next part of a presentation, but
I do not want the audience to be distracted by my work on the computer as I
prepare.
My question is:
Is there an external monitor setting that allows the external monitor to
display one thing(such as an image) continualy, and also allows me to work on
my computer at the same time?