手持ちのPython 3環境で動かしたらちょっと手直しが必要だったので、まずフォーク。

w32example.py

# -*- coding: utf-8 -*-

# http://algomarket.wikidot.com/win32-api-in-python
# `Hello world in python using win32py'
# 手持ちのPython 3環境で動かしたらちょっと手直しが必要だったので、まずフォーク。

from win32api import (GetModuleHandle,)
from win32gui import (WNDCLASS,
                      GetStockObject,
                      RegisterClass,
                      CreateWindow,
                      ShowWindow,
                      UpdateWindow,
                      GetMessage,
                      TranslateMessage,
                      DispatchMessage,
                      PostQuitMessage,
                      BeginPaint,
                      GetClientRect,
                      DrawText,
                      EndPaint,
                      )
from win32con import (WHITE_BRUSH,
                      WS_OVERLAPPEDWINDOW,
                      WS_CAPTION,
                      CW_USEDEFAULT,
                      SW_SHOW,
                      WM_PAINT,
                      WM_DESTROY,
                      CS_VREDRAW,
                      CS_HREDRAW,
                      DT_SINGLELINE,
                      DT_CENTER,
                      DT_VCENTER,
                      )

def OnPaint(hwnd, message, wParam, lParam):
  hdc, ps = BeginPaint(hwnd)
  rect = GetClientRect(hwnd)
  int, rect = DrawText(hdc, u"Hello, Windows 98!" , -1 , rect,
                       DT_SINGLELINE | DT_CENTER | DT_VCENTER)
  EndPaint(hwnd, ps)
  return 0

def OnDestroy(hwnd, message, wParam, lParam):
  PostQuitMessage(0)

message_map = {
                 WM_PAINT: OnPaint,
               WM_DESTROY: OnDestroy,
              }

# have to create hInstance explicitly
hInst = GetModuleHandle()

# create window class structure
szAppName = u"HelloWin"
wndclass = WNDCLASS()
wndclass.style = CS_HREDRAW | CS_VREDRAW
wndclass.lpfnWndProc = message_map
wndclass.cbWndExtra = 0
wndclass.hInstance = hInst
wndclass.hIcon = 0
wndclass.hCursor = 0
wndclass.hbrBackground = GetStockObject(WHITE_BRUSH)
wndclass.lpszMenuName = ''
wndclass.lpszClassName = szAppName
# need encode!

# register window class
hr_registerclass = RegisterClass(wndclass)

# create window
hwnd = CreateWindow(szAppName,
                    u"The Hello Program",
                    WS_OVERLAPPEDWINDOW | WS_CAPTION,
                    CW_USEDEFAULT,
                    CW_USEDEFAULT,
                    CW_USEDEFAULT,
                    CW_USEDEFAULT,
                    0,
                    0,
                    hInst,
                    None) # must be None!
ShowWindow(hwnd, SW_SHOW)
UpdateWindow(hwnd)

# message loop
while True:
  b, msg = GetMessage(hwnd, 0, 0)
  if msg == 0:
    break
  TranslateMessage(msg)
  DispatchMessage(msg)