Using a Slave PC for each Display controlled by a Master PC is the ideal solution. But if resources are limited and your single PC has the oomph to handle the media playing at full frame-rates without hiccups, then you could use only that single PC (Master) as a Slave as well. This single PC is of course equipped with a triple-head graphics card (does any exist???). I use dual-head cards, but have not found a triple-head card yet.
With a triple-head gfx card, you then only need one licence key to run a 3-screen multi-display show with Wings. Note that by a triple-head graphics card (if any exist), I am not referring to the Matrox TripleHead2Go device which works differently.
If you want to learn further how to set-up a 3-display show, I suggest we take this off-line and I can step you through it, perhaps with some screen captures to illustrate. (But I'm having early nights and very early mornings with a full day outdoors till this Sunday...so you'll have to be patient). Else, perhaps Alex can help instead.