If you view at 100% you are seeing all the pixels. AE does not have the option to remove the Comp panel. If you comp has the same frame size as your second display then you will not see all of the image because it will be cropped by the frame of the comp panel.
I'm not sure from your description if this is what you're looking for, but here is a handy shortcut, copied from After Effects Help:
Resize application window or floating window to fit screen. (Press again to resize window so that contents fill the screen.)
There's information about floating windows and panels here.
thanks Rick, I think that did it. The reason is I want to have the composition pixels exactly match the display pixels, and when I render it to a quicktime I want the quicktime to be able to go fullscreen and then the pixels are in exactly the same place.
Its because I am using it to project animations to a sculpture and map the animations to it.
I am having problems locking the composition into the centre of the screen. In Photoshop if you press F the image goes full screen but seems to be locked in the centre. This way I know that the pixels in the image are locked to the pixels on the screen.
Does anyone know a way to lock it in After Effects?