Client Hyper-V is a virtualization product that comes installed with Windows 8, but it's not enabled by default. To enable it follow these steps:
- On the Control Panel, click Programs, and then click Programs and Features.
- Click Turn Windows features on or off.
- Click Hyper-V, click OK, and then click Close.
BTW: There are specific requirements for running Client Hyper-V on Windows 8. See those here: Requirements for Running Hyper-V on Windows 8