Windows Aero is the graphical user interface and the default theme in most editions of Windows Vista and Windows 7 , operating systems released by Microsoft. It is also available in Windows Server 2008. Its name is a backronym for Authentic, Energetic, Reflective and Open. Intended to be a cleaner, more powerful, more efficient and more aesthetically pleasing user interface than the previously used theme (Luna), it includes new translucency, live thumbnails, live icons, animations and eye candy. Aero also encompasses a set of user interface design guidelines for Microsoft Windows.

Steps:

1. Before considering turning Aero on, make sure you're computer has the following requirements:

An OS (operating system) of Windows Vista Premium/Windows 7 or better (Starter and Basic editions will not support Aero)
1 GHz 32-bit (x86) or 64-bit (x64) processor
1 GB of system memory
a DirectX 9 compatible graphics processor with a Windows Display Driver Model (WDDM) driver and a minimum of 128 MB of Video RAM
40 GB hard drive with 15 GB free space

2. Now, on the desktop, right-click and select "Personalize".

3. (For Vista users): Click on "Theme".

4. (For Vista users) A window will appear, with a list of available themes in a drop-down menu, with corresponding illustrations below. The setting should be on "Vista Basic" as default.

(For Win7 users) A window will appear, showing you all the currently installed themes on your computer. In the window, there is a category called Aero Themes. Just scroll down the window if you can't see it.

5. (For Vista users) In the drop-down menu there is an option for "Windows Aero"

6. (for vista users) Click it, then select Apply then OK and you're computer will be configured to Windows Vista Aero.

(for Win7 users) Click your desired aero theme and it will automatically be applied on your desktop.

7. An important note. If you have already done all of this and aero still isn't working. Make sure your video card setting is at 32 bit. If not you will not be able to use the aero features. You can change this under display settings in the personalization menu.