Windows 7 lets you bring up the desktop without taking your hand off your mouse or pointing device, but it's not obvious how until you stumble upon it. In the extreme lower right portion of the screen, at the far-right edge of the taskbar, you'll see a little vertical rectangle with a glossy finish. Hover the mouse pointer over it, and the Windows Desktop appears, letting you inspect it. (You'll still see ghostly outlines of the windows you have open). Move the mouse off the rectangle, and your windows reappear. You can also activate this via the keyboard shortcut 'Win+spacebar'.
Click on the rectangle, though (as opposed to hovering), and you'll minimize all windows, allowing you to interact with the desktop, open folders, and the like. If you don't open or maximize any new windows manually, clicking the rectangle a second time restores the view to the state it was in before you clicked.