This has changed in the Release Preview of Windows 8. As I am typing this, my main monitor is 25" monitor, but I like to have my Kindle app in Metro on my smaller 19" so that I have that as a reference as I am working on the big screen (kind of like having a book next to you). To recap, in Windows 8 Release Preview, to move my Metro app to a different monitor, I move my mouse to the top of the screen and make it turn into a hand. Then, when it does, I drag it in the direction of the monitor that I want it to go to, and it snaps to it. The one thing that I don't like about it is the face that if I wanted to say see it for a second on one monitor to see if it worked better there (I have 4 monitors on my system), I would have to re-select the top, move it, and do it all over again. If they could make it that when you are moving the Metro area from screen to screen it didn't let go of it until you release the mouse button, that would be awesome. Also, you can have only one Metro screen area, so for example, you can say move the Cut the Rope app to your second monitor and have the Kindle app on the primary monitor, they all stay on one monitor, and the Metro home screen that gets brought up when you click on Start will show up on that screen as well. But, thought I would point that out.