The Windows Phone 8 emulator runs as a virtual machine on Hyper-V, a new virtualization technology available in Windows 8.
The Hyper-V on Windows 8 requires that your system supports Second Level Address Translation (SLAT).
Note that if your PC doesn’t support all the prerequisites for running the Windows Phone 8 Emulator, you can still install the Windows Phone 8 SDK and develop apps but can only test on the real device.
Read more about How to verify Your PC if it can run Windows Phone 8 Emulator? @MobileOSGeek.com