You didn't say whether this is on Doze or X Window System on some flavor of UNIX. If it is 'NIX, then you can tell your Window manager which display to write to when you pop a window open. Once it's open, it's a filehandle like any other. You'll need to use a windowing toolkit with your Perl (or C, for that matter). and CPAN has a whole slew of helpful modules (look under User Interfaces) that you can use to talk directly to X and to the Windowing toolkit of your choice (Tk, Gtk, Qt, etc.) on top of it. A reasonably simple one to look at is X11::Fvwm, which talks directly to a simple X window manager with Display-shifting ability.

Someone else will have to help you if it's a Doze system; you can set up multiple monitor cards in Windows and I suspect the place to start would be the ActiveState docs.

In any case, your goal is a good one, and welcome to the Perl community!