If the 5 screens work in Windows, are the 3 x 27" screens set up as a 'single' wide-angle view and the 2 x smaller screens independent of this - i.e. an extension of the Windows 'desktop' onto, say, a left and a right screen?
If so, then FSX should allow you to 'undock' 2 New Views (1 for Instruments + 1 for Console) and 'drag' them individually left and right. I only have 1 extra screen like this and the undocking seems to be the trick.
By the way, +1 on Brett's Welcome! And do let us see your set up - sounds great!
Cheers - Dai.