The Buffalo TeraStation 5200 is a small office NAS that we recently reviewed. We observed that it had a VGA port on the front, which wasn't very useful for a NAS like the TeraStation 5200. It's a different matter with the TeraStation Pro Duo WSS, which looks like the identical twin of the 5200, but instead is equipped with Windows Storage Server 2008 R2 Workgroup Edition.
That is something else than Windows Storage Server 2008 R2 Essentials, which is a version of Windows Home Server. This is the true Windows 2008 R2 Storage Server, without the Dashboard, but with all of the features you expect from Windows Storage Server 2008 R2. This Workgroup version of Windows 2008 R2 Storage Server can handle 50 simultaneous SMB connections. It also functions as an iSCSI target and initiator, which means you can use both as iSCSI client and server.
It has business features such as deduplicating files (Windows Single Instance Storage) which prevent files from being save twice and can save a lot of space. It's also possible to create a distributed file system (DFS). Basically it's also just a smart, compact file server on a Windows network which you can set up as back-up server as well. For that Buffalo included back-up and replication software.