How to cascade windows vertically or horizontally in Windows 7?

Right click on the Taskbar:
Stack windows = vertical
Show windows side by side = horizontal

I guess you mean "Tile vertically or horizontally"?

You can use Aero Snap: move 1 window on the left side of the screen and the other windows on the right side of the screen. Both will maximize to half the size of the screen, making it easy to view both at the same time.