Windows 7 Enterprise is considered an “Upgrade Version” meaning that you have to have a previous version of Windows to activate via our Key Management Server (KMS). Manufacturers set the Windows Marker during the computer’s manufacture. During the KMS activation the BIOS is checked for the Windows Marker. If it is not present it will fail.

To check the windows marker, download and run the Microsoft Genuine Advantage Diagnostic Tool:

http://go.microsoft.com/fwlink/?LinkID=52012

After you launch it, click the “Continue” button in the lower right corner. When it finishes select the “Windows” tab at the top and click the “Copy” button in the lower right corner. Open Notepad and select “Edit” and “Paste”.

Near the bottom of the document you should find the last paragraph starts with the following;

If it looks something like this;