Using "Start | Settings | Control Panel | System | Computer Name Tab | Change..." and setting a new computer name should change the "NV Hostname" in the registry and for ReactOS it does not. In W2K3, I ran Regshot and then changed the computer name (did not allow the reboot) and then ran Regshot again and did a compare and this showed two registry keys changed. I repeated this procedure in ReactOS and this only showed one registry key changed. Next I ran API Monitor in W2K3 and captured all "SetComputerName" calls and changed the computer name (did not allow the reboot) and it showed only one call to SetComputerNameExW using ComputerNamePhysicalDnsHostname for the first parameter and points to netid.dll as the source. The attached patch causes ReactOS to function like Windows 2003 Server in this regard.
Also, on reboot the value in the registry for "NV Hostname" should be copied to "Hostname". I captured a Win2003 Server Process Monitor Bootlog what shows that winlogon.exe is the place where this occurs.
All ReactOS revisions are affected up to and including 0.4.13-dev-531-g4916527.