I am trying to achieve the make use of AD administrative commands such as "Get-ADUser" and "Get-ADComputer" via Powershell. All our domain controllers are Windows 2003 and we have one Windows 2012 Member server. Can I use that server for this purpose or is that mandatory to make the 2012 server a DC?
It is not mandatory, however in order to allow a Windows 2003 Domain Controller to be accessible from the Active Directory Powershell Module the Active Directory Management Gateway Service (Active Directory Web Service for Windows Server 2003 and Windows Server 2008) has to be installed on it.
Please make sure that you read the System Requirements section because there are hotfixes needed to be installed before attempting to install the gateway service. Failure to do so will result in the
This update does not apply to your system error.
I actually wrote a guest post on @WesleyDavid's blog about this. It walks you through the prerequisites and installation on Server 2003 as well as gives a few example commands in the PowerShell cmdlets to get started.
On your 2003 DCs that you wish to run the AD Web Services installer on, you need the .Net 3.5 SP1 framework, plus a couple of hotfixes. You don't need to install this on all of your DCs if you don't want to query all of them.
More details can be found in the "System Requirements" section of this Microsoft Download link