System.Security.Principal.WindowsIdentity.GetCurrent().Name

 Public Function SetServiceUserAccount(ByRef err_text As String, _
   ByVal ServiceName As String, Optional ByVal ServiceStartName As String = vbNullString, _
   Optional ByVal Password As String = vbNullString) As Boolean
    SetServiceUserAccount = True
    Dim sc As New ServiceController(ServiceName)

    ' Get a handle to the SCM database. 
    Dim schSCManager As IntPtr = OpenSCManager(vbNullString, vbNullString, SC_MANAGER_ALL_ACCESS)
    If schSCManager = IntPtr.Zero Then
      SetServiceUserAccount = False
      err_text = "OpenSCManager Error " & RaiseAPIError()
      GoTo ToExit
    End If

    ' Get a handle to the service.
    Dim schService As IntPtr = OpenService(schSCManager, ServiceName, SERVICE_ALL_ACCESS) ' SERVICE_CHANGE_CONFIG
    If schService = IntPtr.Zero Then
      SetServiceUserAccount = False
      err_text = "OpenService Error " & RaiseAPIError()
      GoTo ToExit
    End If

    ' надо б остановить если запущен, потом же проверять придется
    Dim Status As SERVICE_STATUS

    ' Query Service Status
    If QueryServiceStatus(schService, Status) = False Then
      SetServiceUserAccount = False
      err_text = "QueryServiceStatus Error " & RaiseAPIError()
      GoTo ToExit
    End If

    If Status.dwCurrentState <> SERVICE_STOPPED Then
      ' Stop the service
      If ControlService(schService, SERVICE_CONTROL_STOP, Status) = False Then
        SetServiceUserAccount = False
        err_text = "ControlService Error " & RaiseAPIError()
        GoTo ToExit
      End If
      sc.WaitForStatus(ServiceControllerStatus.Stopped, New TimeSpan(0, 0, 10))
    End If

    ' Change the service account name
    If ChangeServiceConfig(schService, SERVICE_NO_CHANGE, SERVICE_NO_CHANGE, SERVICE_NO_CHANGE, _
     , , , , ServiceStartName, Password, ) = False Then
      SetServiceUserAccount = False
      err_text = "ChangeServiceConfig Error " & RaiseAPIError()
      GoTo ToExit
    End If

    ' Надо б проверить, а вдруг с паролем ошиблись?
    ' Start the service
    If StartService(schService, 0, IntPtr.Zero) = False Then
      SetServiceUserAccount = False
      err_text = "StartService Error " & RaiseAPIError()
      GoTo ToExit
    End If
    sc.WaitForStatus(ServiceControllerStatus.Running, New TimeSpan(0, 0, 10))

    ' Stop the service
    If ControlService(schService, SERVICE_CONTROL_STOP, Status) = False Then
      SetServiceUserAccount = False
      err_text = "ControlService Error " & RaiseAPIError()
      GoTo ToExit
    End If
    sc.WaitForStatus(ServiceControllerStatus.Stopped, New TimeSpan(0, 0, 10))

ToExit:
    If schService <> IntPtr.Zero Then CloseServiceHandle(schService)
    If schSCManager <> IntPtr.Zero Then CloseServiceHandle(schSCManager)
  End Function