Hello John A Smith, To my knowledge I don’t think there is any real change but would have to look up on Microsoft site to be sure.  As far as I know I am not sure why 2012 isn’t an option.  I think it is due to we haven’t created any drivers for 2012 yet but I can’t confirm that this is the reason or not.   Please let us know if you have any other questions.
We currently have a Dell PowerVault 740N.  It is primarily a file server but is also being used for FTP and it is running a few Windows apps.  I have it connected to a monitor, keyboard and mouse so it is fully functional as a stand alone workstation.  I am looking at the NX400 but I need to confirm it will do at least the same as our 740N.  I do realize that the NX400 will not act as a Domain server or a DNS server but other than that will there be any other use restrictions?  Dell's Small Business sales person didn't have a clue. Thank you.
Can I use the NX400 as a workstation and file server?