It's possible to play on one monitor. It's not pretty though.
Not to be picky, but it CAN be very pretty, depending on your screen

My default five boxing setup is two machines these days - one "slave" running two WoWs side-by-side on a basic 1650x1050 22" monitor, and my "main" machine running as 2+1 on my 27" 1920x1200.

I never need to see anything on the drone screens except their focus targets (I use that for CC and cross-healing in a multi-healer group). I can see more than enough on each screen for quest turn-ins, etc.

I had a play with 1+4 on my main machine at the weekend too, and it looks great!

One main at 1200x1024 and four tiny drones down the side of that window looks really nice. I can still see enough to do almost everything, and if it gets tight (like reading the latest abusive whisper) I can simply use Keyclone's PiP function to pop one of the drones into the main window for a while.

Likewise if the main dies - just pop the "next in command" into the main window and carry on.

In fact, a single screen using that setup will be my new mode for boxing once I get a third disk into my rig to alleviate the loading times when zoning.

Of course, I probably wouldn't want to do that with a 1200x1024 screen 8)