Is this possible to be done automatically, and have the monitors know what to do when they encounter a different sized image,
I have looked..REALLY looked for just such a program. I have yet to find it. Ultramon is good...but right before I went to buy it, I discovered my nVidia allowed me to use seperate walls and a few things I didn't know about previously. Sorry, I couldn't help, but I will keep looking and let you know if I find something.
The only other option I can think of is wether or not such a thing could be scripted in DesktopX. I suppose the trick would be teaching it to know the difference in wall resolutions and how to apply them.