The Split-screen view has been present in previous versions of Office but with the new 2007 layout, you might get confused to find this. And there are generally two ways to do this.
You can still simply click and drag the Split view slider located at the beside the right-most part of the ruler. Double-clicking it will automatically split your screen in half.
you can also Click View and the Split button. This will allow you to split the screen horizontally to your desired size.
Now you can view two parts of the document at the same time.To restore the screen to just one pane, just double-click on the Split view slider.