Windows Media Center is absent in Windows 10 Technical Preview , but some users have restored Windows Media Center by using the product key that they purchased for use in Windows 8.1. This will prevent you from getting updates and future builds for Windows 10 Technical Preview.
When the Media Center product key is used to add Media Center to Windows 10, the system subsequently identifies itself as running “Windows 8.1 Pro with Media Center”, along with a warning that the OS has not been activated. It also prevents users from getting updates and patches to the Windows 10 preview.
Microsoft has acknowledged the problem, and a Support Engineer posted an apology on the company’s forum urging other users to avoid this.
We apologize for not catching this before we launched Tech Preview; we did not intend for you to be able to use a purchased product key on a preview build.
We do not recommend adding Media Center to Windows 10 Technical Preview as using a purchased product key will also prevent you from getting updates and future builds for Windows 10 Technical Preview.
To make sure you get updates for Tech Preview, we recommend that you download the ISO file and perform an in-place upgrade to re-install Windows 10 Technical Preview.
The post ends by encouraging users to download the Technical Preview ISO file to “perform an in-place upgrade to re-install Windows 10 Technical Preview.”