Saitek provides drivers and some very rudimentary instruments - basically everything you need but it doesn't look very "real".
But there are many freely available instruments on the net - just search for Saitek FIP. Installation is easy.

just like steffennes said, get drivers from saitek and when you start fsx, p3d etc they start automatically.
but the best is to look for them at e.g.: simviation, essential gauges, fsxtimes (unfortunately no longer free but very well done) etc.
the most important directories are then:
C:\Program Files\Saitek\DirectOutput - (only for the standard images in idle state)
C:\Program Files (x86)\Saitek\DirectOutput - (here are the actual gauges)
and in the SaiFlightSimX.xml detei you set everything (incl. buttons)

Please provide a link. The initial images of the instruments are sharp and look real. How did you get the displays to work? They don't come alive for me......Help please. kostsenior@gmx.ch