You shouldn't need special software to do that. Windows on its own will recognize multiple displays and treat each individually. However, if you're using NVidia Surround or AMD Eyefinity, then it treats all your displays as a single unit so if you use one full-screen application, like a game, then that's the only one you will see.
EDIT: Ah, yes, you could be running the game in total full screen, not full screen windowed, and that could blank out the second screen. Also, you might want to check your game for things like disabling the Windows key or Windows shortcuts.