The x86 Android* 4.2 (Jelly Bean) emulator system image enables you to run an emulation of Android on your development machine. In combination with the Android SDK, you can test your Android applications on a virtual Android device based on Intel Architecture.
In order to install the emulator image add-on, you can use the Android SDK Manager (Recommended Method):
Alternately, you can download the binary zip file and unzip and copy the included directory into the add-ons directory of your Android SDK installation. (Note that this method does not allow for automatic updates of the add-on):
System image binaries
System image source