This set of features is called Windows Aero. It is available in Vista and Windows 7 only. The key characteristics of these features are the following:
*Window borders are translucent, such that you can see the window behind it through its background
*When you hover the cursor over a tab, it shows its contents
*When you press Alt + Tab, it shows thumbnails of your active programs
*WIndows animation when opening or closing
The new feature in WIndows 7 is the Show Desktop icon located in the bottom right of the screen. When you click it, all open windows disappear to reveal the desktop page.