There's no standalone Viewpoint software, it's always preinstalled as an appliance.
Some of the TD Express downloads include Viewpoint, you just have to assign more RAM to the VM and start it manually: http://downloads.teradata.com/download/database/te
The most recentt version is
There are actually two variants of the Viewpoint bundled solution, the Viewpoint Appliance which is the multi-system management console that can be configured in HA clusters. The second is the VMS (Virtualized Management Server) Viewpoint that is available for certain platforms but is limited to single system monitoring. As Dieter mentions however, there is no "software only" Viewpoint offering. If you are just looking to learn about it, download Teradata Express which has a single system bundled Viewpoint instance.