Windows 7 Administrator user doesn't have Admin rights

Even though you are as an administrator, on Windows 7, you are actually not a full administrator in normal context.

From Technet:

When an administrator logs on to a computer that is running Windows 7 or Windows Vista, the user is assigned two separate access tokens. Access tokens, which contain a user's group membership and authorization and access control data, are used by the Windows operating system to control what resources and tasks the user can access. The access control model in earlier Windows operating systems did not include any failsafe checks to ensure that users truly wanted to perform a task that required their administrative access token. As a result, malicious software could install on users' computers without notifying the users. (This is sometimes referred to as a "silent" installation.)

I highly recommend against it, but you can try to disable the "User Account Control: Run all administrators in Admin Approval Mode". You can change that behavior by modifying the EnableLUA value in the following key to 0 in the registry, and restarting the computer:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System

The alternative is to right click the Command Prompt icon and click Run As Administrator; otherwise you're running in a user context.