It's actually easier that I thought, although you really need a stronger video card to drive two screens properly. More on that latter.
You start by setting up Windows for multiple monitor support and for extended desktop, where Windows treats the two monitors like one extended screen. Then you launch FSX and start a mission or free-flight or whatever normally. Once in the simulator, you activate the menu, go the view menu, select new view and then virtual cockpit. That opens a small window, sort of like a picture-in-picture on the main monitor, which you then drag to the second monitor and resize to fill the screen. Finally, you adjust the view angle on each screen so they line up correctly or as close as you can get them.
Here's a photo of the results:
A laptop with widescreen sits a good bit lower than a standard monitor on a stand, so I had to put a phone book under the laptop to compensate. The effect is still not perfect, but you clearly get a better view than with a single screen. Imagine three screens, and the peripheral vision effect you get from that!
As I mentioned earlier, my laptop's video capabilities were not made for gaming, so forcing it to output twice as many pixels resulted in a noticeable reduction in frame rate, to the point that it made flying more difficult. I still managed to take off, circle around a bit and land without crashing, but the landing was not pretty. The lag between control inputs and the screen updates was hard to adjust to so there was a lot of over-correction on the approach.
To make this work with acceptable frame rates I'd need to reduce the graphics quality a good bit. Then the question becomes whether that's worth the extra screen real estate you gain from this setup. With a desktop system and a gaming video card, you probably wouldn't have to make the trade-off.
The other thing I noticed, and perhaps there's a work around, is that only one screen is "active" at any given time, and only that screen pans when you change your point of view (looking left or right for example). Thus, any effort to look around breaks the illusion that you're looking at one really wide screen. Maybe there's a way to lock the screens so they pan together, but I've not figured that out yet.
More testing to follow...
