Window not visible

The following SDK application works fine using gcc-

 gcc -mwindows simple_window.c -o first_sdk.c

But compiling with VC6 my application window is invisible.

 Nmake -f makefile

Attached are the source code (first_sdk.c) and
the makefile I am using to compile code.

How do I set a window visible?

/* File: first_sdk.c
 *
 * Description:
 *
 *
 * Created:
 * 12 Feb 2008 -
 */
#include <windows.h>

LONG WINAPI WndProc(HWND, UINT, WPARAM, LPARAM);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
           LPSTR lpszCmdLine, int nCmdShow){
  WNDCLASS wc;
  HWND hwnd;
  MSG msg;

  wc.style = 0; /* Class style */
  wc.lpfnWndProc = (WNDPROC) WndProc; /* Window procedure address */
  wc.cbClsExtra = 0; /* Class extra bytes */
  wc.hInstance = hInstance; /* Window extra bytes */
  wc.hIcon = LoadIcon(NULL, IDI_WINLOGO); /* Icon handle */
  wc.hCursor = LoadCursor (NULL, IDC_ARROW); /* Cursor handle */
  wc.hbrBackground = (HBRUSH) (COLOR_WINDOW + 1); /* Background color
*/
  wc.lpszMenuName = NULL; /* Menu name */
  wc.lpszClassName = "MyWndClass"; /* WNDCLASS */

  RegisterClass (&wc);

  hwnd = CreateWindow("MyWndClass", /* WNDCLASS */
              "SDK Application", /* Window title */
              WS_OVERLAPPEDWINDOW, /* Window style */
              CW_USEDEFAULT, /* Horizontal position */
              CW_USEDEFAULT, /* Vertical position */
              CW_USEDEFAULT, /* Initial width */
              CW_USEDEFAULT, /* Initial height */
              HWND_DESKTOP, /* Handle of parent window
*/
              NULL, /* Menu handle */
              hInstance, /* Application's instance
handle */
              NULL /* Window-creation data */
              );

  ShowWindow(hwnd, nCmdShow);
  UpdateWindow(hwnd);

  while(GetMessage(&msg, NULL, 0, 0)){
    TranslateMessage(&msg);
    DispatchMessage(&msg);
  }
  return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam,
             LPARAM lParam){
  PAINTSTRUCT ps;
  HDC hdc;

  switch(message){

  case WM_PAINT:
    hdc = BeginPaint(hwnd, &ps);
    Ellipse (hdc, 0, 0, 200, 100);
    EndPaint(hwnd, &ps);
    return 0;

  case WM_DESTROY:
    PostQuitMessage(0);
    return 0;
  }
  return DefWindowProc(hwnd, message, wParam, lParam);
}

# File: makefile
#
# Description:
#
#
# Created:
# 15 Feb 2008 -
#
# Nmake macros for building Windows 32-Bit apps
!include <win32.mak>

PROJ = first_sdk

all: $(PROJ).exe

# Define project specific macros
PROJ_OBJS= first_sdk.obj
BASE_OBJS =
EXTRA_LIBS=
GLOBAL_DEP=
RC_DEP=

# Inference rule for updating the object files
..c.obj:
  $(cc) $(cdebug) $(cflags) $(cvars) $*.c

# Build rule for EXE
$(PROJ).EXE: $(BASE_OBJS) $(PROJ_OBJS)
    $(link) $(linkdebug) $(guilflags) \
    $(BASE_OBJS) $(PROJ_OBJS) $(guilibs) $(EXTRA_LIBS) \
    -out:$(PROJ).exe $(MAPFILE)