XFree86 On Computer Projectors?

Bruce Ingalls asks: "Ask Slashdot ran some computer projector recommendations back on June 4, concerning quality, cost of replacing bulbs, but I have have had problems connecting XFree86 on a laptop to computer projectors. These projectors always work in console mode, or with Microsoft Windows. I find that a projector will work with some Linux laptops, but not others. One workaround that sometimes works is to start X where it displays to the external screen only, and then hit the hotkeys to enable the laptop's internal screen, afterwards. Any other recommendations?"