Here is how to change a Windows KMS license to a MAK license.

First run this command from a dos prompt and put in your MAK license Key.

slmgr -ipk xxxxx-xxxxx-xxxxx-xxxxx-xxxxx
http://support.microsoft.com/kb/929826/

Next. Go to system's properties in the control panel and click on activate windows now. After click on it you will activate it with a MAK license.