You can do targeted AOE with two computers and ISBoxer. I ran with this exact setup for the past few months (Main on one machine, other 4 on the second). Mouse broadcasting works fine if both are the same resolution (WoW window resolution, not Windows resolution).

IIRC InnerSpace basically tells it to click at say position 100,100 in all windows relative to the WoW window, not your desktop. So even if you have one machine with a larger monitor, as long as you run WoW in a window that is the same size as the smaller LCDs you will be fine.