I'm not sure if this will help you or not, But I would switch them.

at least that's what I did, and it worked well for me.

For example, play the main on the 19" and put the 4 others on the 23" , since the 23" has more screen space.

as far as PiP and settings like that, I am not sure, I'm not at my machine with ISboxer. But the video card is more than enough I would imagine.

Stephen