So it is a "Server Core" installation, you didn't mention that.
So on the Server Core machine, type:
Net use z: "\\oldsever\c$" or d$ or whatever drive letter the vhd file sits in on the old server, the do a "cd z:" and then do a "copy filename.vhd d:\newpath\file.vhd" where the new path is the new path that you want the file to be copied to.
It is the same as moving files around from the command line of a regular windows installation.