To implement Microsoft Deployment Toolkit (MDT), one must have a properly provisioned system on which we can lay down the Windows Assessment and Deployment Kit (Windows ADK) and MDT install files. It must have space, CPUs, some amount of RAM, and most importantly, quick network links to other systems.
All the particulars around these requirements of course depend on what you are using MDT for. Are you building a golden image with which you will deploy via another deployment system? Are you implementing a deployment scenario where you need to deploy to laptops, desktops, medical imaging systems, and point-of-sale devices at multiple sites around the world, all from one infrastructure?