Ah, I see.
Windows itself views them as separate, but by going in through the nvidia drivers screen, it does something different. Windows treats it as a single monitor somehow. The task bar starts on one screen with the Start Button, stretches all the way over to the opposite side of the other screen and ends with the systray/clock.
That's the only reason I mention it, somehow nvidia makes windows thing it's running as a single display (at least, seems that way to me, I don't really know).