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#11
That is correct. You cannot "create" a domain on a Windows 7 machine. Windows 7, XP, Vista, etc. are all client operating systems. Only a server operating system can be used to create a domain, such as Windows Server 2003, 2008, etc. Client operating systems can join a domain, but not create them.
So for your Windows 7 machine to be a part of a domain, you will need at least one other machine with a server operating system on it.
You haven't told us yet what you are trying to accomplish or why you think you need a domain on your machine. You may be going in the wrong direction and we may be able to help.