diff --git a/api/boinc_api.C b/api/boinc_api.C
index a37f9fbc96..12a33aefc2 100644
--- a/api/boinc_api.C
+++ b/api/boinc_api.C
@@ -20,8 +20,11 @@
 // Code that's in the BOINC app library (but NOT in the core client)
 // graphics-related code goes in graphics_api.C, not here
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
+#endif
+
+#ifdef _WIN32
 #include "version.h"
 #else
 #include "config.h"
diff --git a/api/graphics_impl.C b/api/graphics_impl.C
index 1d29cd518a..334f6b4eeb 100755
--- a/api/graphics_impl.C
+++ b/api/graphics_impl.C
@@ -25,8 +25,11 @@
 
 #include "config.h"
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
+#endif
+
+#ifdef _WIN32
 extern void win_graphics_event_loop();
 #else
 #include <cstring>
diff --git a/api/gutil.C b/api/gutil.C
index 6e3c95b044..165a0ec38f 100755
--- a/api/gutil.C
+++ b/api/gutil.C
@@ -17,11 +17,12 @@
 // or write to the Free Software Foundation, Inc.,
 // 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
-//extern "C"{
+#endif
+
+#ifdef _WIN32
 #include "jpeglib.h"
-//}
 #include "bmplib.h"
 #include "tgalib.h"
 #endif
diff --git a/api/reduce_lib.C b/api/reduce_lib.C
index c0a392d9d7..c1a5929b1c 100644
--- a/api/reduce_lib.C
+++ b/api/reduce_lib.C
@@ -19,8 +19,11 @@
 
 // shared-library part of the implementation of REDUCE
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
+#endif
+
+#ifdef _WIN32
 #include <GL/gl.h>
 #endif
 
diff --git a/api/reduce_main.C b/api/reduce_main.C
index 572eb57be5..df87dfb006 100644
--- a/api/reduce_main.C
+++ b/api/reduce_main.C
@@ -16,8 +16,11 @@
 
 // main-program part of the implementation of REDUCE
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
+#endif
+
+#ifdef _WIN32
 #include <GL/gl.h>
 #endif
 
diff --git a/api/windows_opengl.C b/api/windows_opengl.C
index 2a0cd1ad5d..3609735559 100755
--- a/api/windows_opengl.C
+++ b/api/windows_opengl.C
@@ -10,7 +10,10 @@
  * Visit My Site At nehe.gamedev.net
  * Adapted to BOINC by Eric Heien
  */
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
+#endif
+
 
 #include "diagnostics.h"
 #include "boinc_api.h"
diff --git a/checkin_notes b/checkin_notes
index 00ed8c6149..0a5cfb9be7 100755
--- a/checkin_notes
+++ b/checkin_notes
@@ -9127,3 +9127,34 @@ David  14 July 2005
 
     sched/
         sched_send.C
+
+Rom    14 July 2005
+    - Make the requirements for precompiled headers on Windows optional.
+
+    api/
+        boinc_api.C
+        graphics_impl.C
+        gutil.C
+        reduce_lib.C
+        reduce_main.C
+        windows_opengl.C
+    client/win/
+        StdAfx.h
+    lib/
+        app_ipc.C
+        boinc_cmd.C
+        diagnostics.C
+        exception.C
+        filesys.C
+        gui_rpc_client.C
+        hostinfo.C
+        md5_file.C
+        mem_usage.C
+        mfile.C
+        miofile.C
+        network.C
+        parse.C
+        prefs.C
+        proxy_info.C
+        shmem.C
+        util.C
diff --git a/client/win/StdAfx.h b/client/win/StdAfx.h
index 775c445cf0..f2999c27c0 100644
--- a/client/win/StdAfx.h
+++ b/client/win/StdAfx.h
@@ -3,8 +3,8 @@
 //      are changed infrequently
 //
 
-#if !defined(AFX_STDAFX_H__B4B76702_EF2D_4BFC_869D_3F7E2CBE9FFC__INCLUDED_)
-#define AFX_STDAFX_H__B4B76702_EF2D_4BFC_869D_3F7E2CBE9FFC__INCLUDED_
+#if !defined(_AFX_STDAFX_H_)
+#define _AFX_STDAFX_H_
 
 #if _MSC_VER > 1000
 #pragma once
@@ -184,4 +184,4 @@
 //{{AFX_INSERT_LOCATION}}
 // Microsoft Visual C++ will insert additional declarations immediately before the previous line.
 
-#endif // !defined(AFX_STDAFX_H__B4B76702_EF2D_4BFC_869D_3F7E2CBE9FFC__INCLUDED_)
+#endif // !defined(_AFX_STDAFX_H_)
diff --git a/lib/app_ipc.C b/lib/app_ipc.C
index 3ddbe23cbe..e21e653bc6 100755
--- a/lib/app_ipc.C
+++ b/lib/app_ipc.C
@@ -17,7 +17,7 @@
 // or write to the Free Software Foundation, Inc.,
 // 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
 #endif
 
diff --git a/lib/boinc_cmd.C b/lib/boinc_cmd.C
index 7338cb4d98..97ed8efd9f 100644
--- a/lib/boinc_cmd.C
+++ b/lib/boinc_cmd.C
@@ -24,10 +24,11 @@
 //
 // See help() below for a list of commands.
 
-
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
-#else
+#endif
+
+#ifndef _WIN32
 #include <cstdio>
 #include <unistd.h>
 #endif
diff --git a/lib/diagnostics.C b/lib/diagnostics.C
index f41b772af5..a85cce4479 100644
--- a/lib/diagnostics.C
+++ b/lib/diagnostics.C
@@ -20,6 +20,10 @@
 // Stuff related to stderr/stdout direction and exception handling;
 // used by both core client and by apps
 
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
+#include "boinc_win.h"
+#endif
+
 #ifndef _WIN32
 #include <cstdio>
 #include <cstdarg>
diff --git a/lib/exception.C b/lib/exception.C
index 4e9e78497b..fb83075a7a 100644
--- a/lib/exception.C
+++ b/lib/exception.C
@@ -17,7 +17,7 @@
 // or write to the Free Software Foundation, Inc.,
 // 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
 #endif
 
diff --git a/lib/filesys.C b/lib/filesys.C
index db15b61e8b..41cdc2f342 100755
--- a/lib/filesys.C
+++ b/lib/filesys.C
@@ -17,6 +17,10 @@
 // or write to the Free Software Foundation, Inc.,
 // 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
+#include "boinc_win.h"
+#endif
+
 #ifndef _WIN32
 #include <cstdio>
 #include <fcntl.h>
diff --git a/lib/gui_rpc_client.C b/lib/gui_rpc_client.C
index d499dc82dc..dc774ffbd9 100644
--- a/lib/gui_rpc_client.C
+++ b/lib/gui_rpc_client.C
@@ -17,6 +17,10 @@
 // or write to the Free Software Foundation, Inc.,
 // 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
+#include "boinc_win.h"
+#endif
+
 #ifdef _WIN32
 #include "version.h"
 #else
diff --git a/lib/hostinfo.C b/lib/hostinfo.C
index 541b8abe72..411a1e50e4 100644
--- a/lib/hostinfo.C
+++ b/lib/hostinfo.C
@@ -17,7 +17,7 @@
 // or write to the Free Software Foundation, Inc.,
 // 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
 #endif
 
diff --git a/lib/md5_file.C b/lib/md5_file.C
index ff0e08c20f..4c8e4206e8 100644
--- a/lib/md5_file.C
+++ b/lib/md5_file.C
@@ -17,7 +17,7 @@
 // or write to the Free Software Foundation, Inc.,
 // 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
 #endif
 
diff --git a/lib/mem_usage.C b/lib/mem_usage.C
index 638830e726..c004dc67a1 100644
--- a/lib/mem_usage.C
+++ b/lib/mem_usage.C
@@ -17,9 +17,11 @@
 // or write to the Free Software Foundation, Inc.,
 // 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
-#else
+#endif
+
+#ifndef _WIN32
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
diff --git a/lib/mfile.C b/lib/mfile.C
index dd6633696d..9cd3735f81 100644
--- a/lib/mfile.C
+++ b/lib/mfile.C
@@ -17,7 +17,7 @@
 // or write to the Free Software Foundation, Inc.,
 // 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
 #endif
 
diff --git a/lib/miofile.C b/lib/miofile.C
index 77e68d4771..ec53d91d7f 100644
--- a/lib/miofile.C
+++ b/lib/miofile.C
@@ -17,7 +17,7 @@
 // or write to the Free Software Foundation, Inc.,
 // 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
 #endif
 
diff --git a/lib/network.C b/lib/network.C
index dc819d4bcf..7603f6faf8 100644
--- a/lib/network.C
+++ b/lib/network.C
@@ -17,6 +17,10 @@
 // or write to the Free Software Foundation, Inc.,
 // 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
+#include "boinc_win.h"
+#endif
+
 #ifndef _WIN32
 #include <unistd.h>
 #include <cstdio>
diff --git a/lib/parse.C b/lib/parse.C
index 0e7d2e3d3b..f5c35c9075 100644
--- a/lib/parse.C
+++ b/lib/parse.C
@@ -24,6 +24,10 @@
 // by the BOINC scheduling server or client.
 // Could replace this with a more general parser.
 
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
+#include "boinc_win.h"
+#endif
+
 #ifndef _WIN32
 #include <cstring>
 #include <cstdlib>
diff --git a/lib/prefs.C b/lib/prefs.C
index 85336830df..54a053d87d 100644
--- a/lib/prefs.C
+++ b/lib/prefs.C
@@ -17,6 +17,10 @@
 // or write to the Free Software Foundation, Inc.,
 // 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
+#include "boinc_win.h"
+#endif
+
 #ifndef _WIN32
 #include <cstdio>
 #include <cstring>
diff --git a/lib/proxy_info.C b/lib/proxy_info.C
index eea91b2447..e3317f3c1b 100644
--- a/lib/proxy_info.C
+++ b/lib/proxy_info.C
@@ -17,7 +17,7 @@
 // or write to the Free Software Foundation, Inc.,
 // 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
 #endif
 
diff --git a/lib/shmem.C b/lib/shmem.C
index 94f0a3591f..63927d369f 100755
--- a/lib/shmem.C
+++ b/lib/shmem.C
@@ -19,7 +19,7 @@
 
 // interfaces for accessing shared memory segments
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
 #include "boinc_win.h"
 #endif
 
diff --git a/lib/util.C b/lib/util.C
index cf5399b941..895fbc2606 100755
--- a/lib/util.C
+++ b/lib/util.C
@@ -17,6 +17,10 @@
 // or write to the Free Software Foundation, Inc.,
 // 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
+#if defined(_WIN32) && !defined(__STDWX_H__) && !defined(_BOINC_WIN_) && !defined(_AFX_STDAFX_H_)
+#include "boinc_win.h"
+#endif
+
 #ifdef _WIN32
 #define M_LN2      0.693147180559945309417
 #endif