Turn off the computer
Plug in the second monitor
Turn on the computer. You may have the image flash between either screen.
Sign in
Go to control panel and find the display settings bit, or right click the desktop and choose 'personalise' which should get you to the same place.
Ensure you are on the Display Settings page
Click on the image of the second monitor
Press 'extend the desktop onto this monitor'
There may be flashing.
If it does work, then you can now move tabs and programs onto this screen, just shrink the opened program (Besides the X to close a program is the image with 2 squares, this shrinks the program, then you can drag it over to the other screen).
If that works fine, then just load up FSX.
Go to the display settings in FSX and where you can choose the FPS and resolution, you can then select the display device.

The first monitor will have a display device of something like:

0: nVidia 8600GTS

The second monitor will have:

1: nVidia 8600GTS

(That is, if you have an 8600GTS, it will give you the correct graphics card for your computer)


Choose the second monitor and set up the display for that screen. I think you have to have the resolution the same for both monitors otherwise it can look choppy and you may get some poor results.

After that, just load up a flight.