full screen mode jerky, windowed mode smooth on dual monitors

Hi awl: I recently started running dual monitors. I noticed in FSX that in full screen mode the simulation is jerky, I see artifacts and frame rate is down. I presumed this would happen since my video card is now driving dual displays with different information on each. Than I stumbled upon the fact that in FSX Window mode my animation is very smooth. I see no artifacts and no jerkiness on either display. I have the FSX window mode maximized so it fills both monitors.WHAT GIVES? this is counterintuitive. Shouldn't full screen mode give better frame rates?I would give you frame rate numbers, but darn it all I keep forgetting the key combination for frame rate.I am running on an Nvidia 7600gs 512meg card. I have it setup in dual monitor mode in windows using the vertical monitors selection. ( as 1 large vertical monitor)In windows display settings I have 1024x1536x32 resolution selected. Inside FSX I have this same resolution selected.I am presuming I have something configured wrong, but.... what?any help would be appreciated.-Stampee