i tried it with MTW when it first came out with Geforece 440 (or something like that, i think it was a 64MB card)
my results => the main screen (monitor 1) played MTW, the second screen (monitor 2) showed regular windows XP screen (well just the tool bar on the bottom).
I don't see any reason to do this, if you do you will soon find out how frustrating this setting is. Because every time you move the mouth all the way to the right of the MTW screen in apears on Monitor 2. Monitor one keeps on spining (in battle ).