I would suggest you rethink your plan, though. A lot of folks
have large, high-res monitors; do you really want your help system
to be 1600 by 1200 ? This can be really annoying to users who don't
like their screen taken over.
Instead, I would test for the users' screen size, and go
fullscreen if necessary, otherwise use an appropriate size for your
help system for users of larger monitors.