New laptops often are shipped with the Windows product key stored in the EFI/BIOS/whatever. The result is that you don't get a product key prompt any more. Great for reinstalls, as copying the key by hand is very error-prone. However, when I wanted to install a fresh Win8 Pro version, the embedded "Home" version key wasn't accepted and the installer did not ask for another key. It was simply impossible to install Windows 8 Pro.

This blog post will describe how I got it installed in the end.