Two is kinda useless for gaming, because there's a big bar right in the middle of your overall view. You really need 3 for a good gaming setup.
But, the advantage of two monitors is a lot more apparent when working on other stuff. I set this up today because I was getting really frustrated with having to click back and fourth between microsoft office, firefox, alice, and windows media player every 10 seconds or less. Now, I can have firefox or a tutorial video open in one window, while I can keep working seamlessly on the other screen.
Basically, it's like having two computers, but with the ability to copy and paste from one to the other.
Don't get me wrong, it is mostly unnecessary. But it does help a little bit whenever you have more than 1 or 2 windows open. And it looks really awesome with this background. Keep in mind, both my screens are 24" diagonally, so it's huge.
