--- a/console.c	Sun Sep 12 21:49:38 2004 +0000
+++ b/console.c	Sun Sep 12 22:03:14 2004 +0000
@@ -730,7 +730,7 @@
 
 bool IConsoleCmdHookHandle(_iconsole_cmd * hook_cmd, byte type)
 {
-	bool (*proc)(_iconsole_cmd * hook_cmd);
+	bool (*proc)(_iconsole_cmd * hook_cmd) = NULL;
 	switch (type) {
 	case ICONSOLE_HOOK_AFTER_EXEC:
 		proc = hook_cmd->hook_after_exec;
@@ -741,11 +741,9 @@
 	case ICONSOLE_HOOK_ACCESS:
 		proc = hook_cmd->hook_access;
 		break;
-	default:
-		proc = NULL;
-		break;
+	default: return true;
 	}
-	if (proc == NULL) return true;
+
 	return proc(hook_cmd);
 }
 

--- a/functions.h	Sun Sep 12 21:49:38 2004 +0000
+++ b/functions.h	Sun Sep 12 22:03:14 2004 +0000
@@ -275,6 +275,7 @@
 void LoadFromConfig();
 void SaveToConfig();
 int ttd_main(int argc, char* argv[]);
+byte GetOSVersion();
 
 void DeterminePaths();
 char * CDECL str_fmt(const char *str, ...);

--- a/hal.h	Sun Sep 12 21:49:38 2004 +0000
+++ b/hal.h	Sun Sep 12 22:03:14 2004 +0000
@@ -38,7 +38,7 @@
 	const char *name;
 	const char *longname;
 	const void *drv;
-	uint flags;
+	uint32 flags;
 } DriverDesc;
 
 enum {

--- a/ttd.c	Sun Sep 12 21:49:38 2004 +0000
+++ b/ttd.c	Sun Sep 12 22:03:14 2004 +0000
@@ -52,6 +52,7 @@
 uint32 _pixels_redrawn;
 bool _dbg_screen_rect;
 bool disable_computer;
+static byte _os_version = 0;
 
 void CDECL error(const char *s, ...) {
 	va_list va;
@@ -192,7 +193,7 @@
 	const DriverDesc *best = NULL;
 	int best_pri = -1;
 	do {
-		if ((int)(dd->flags&DF_PRIORITY_MASK) > best_pri) {
+		if ((int)(dd->flags&DF_PRIORITY_MASK) > best_pri && _os_version >= (byte)dd->flags) {
 			best_pri = dd->flags&DF_PRIORITY_MASK;
 			best = dd;
 		}
@@ -571,6 +572,7 @@
 
 	// Sample catalogue
 	DEBUG(misc, 1) ("Loading sound effects...");
+	_os_version = GetOSVersion();
 	MxInitialize(11025, "sample.cat");
 
 	// This must be done early, since functions use the InvalidateWindow* calls

--- a/unix.c	Sun Sep 12 21:49:38 2004 +0000
+++ b/unix.c	Sun Sep 12 22:03:14 2004 +0000
@@ -353,6 +353,13 @@
 	{     NULL,	NULL,										NULL,										0}
 };
 
+/* GetOSVersion returns the minimal required version of OS to be able to use that driver.
+	 Not needed for *nix. */
+byte GetOSVersion()
+{
+	return 1; // any arbitrary number bigger then 0
+}
+
 bool FileExists(const char *filename)
 {
 	return access(filename, 0) == 0;

--- a/w32dm.c	Sun Sep 12 21:49:38 2004 +0000
+++ b/w32dm.c	Sun Sep 12 22:03:14 2004 +0000
@@ -64,8 +64,8 @@
 {
 	if (InitDirectMusic() == true)
 		return(0);
-	else
-		return("Unable to initialize DirectMusic");
+
+  return("Unable to initialize DirectMusic");
 }
 
 static void DMusicMidiStop()
@@ -113,4 +113,4 @@
 	SetVolume(vol);
 }
 
-#endif
+#endif /* WIN32_ENABLE_DIRECTMUSIC_SUPPORT */

--- a/w32dm2.cpp	Sun Sep 12 21:49:38 2004 +0000
+++ b/w32dm2.cpp	Sun Sep 12 22:03:14 2004 +0000
@@ -302,4 +302,4 @@
 }
 #endif
 
-#endif // WIN32_ENABLE_DIRECTMUSIC_SUPPORT
+#endif /* WIN32_ENABLE_DIRECTMUSIC_SUPPORT */

--- a/win32.c	Sun Sep 12 21:49:38 2004 +0000
+++ b/win32.c	Sun Sep 12 22:03:14 2004 +0000
@@ -1775,33 +1775,67 @@
 	DeleteFile(path);
 }
 
+#define Windows_2000		5
+#define Windows_NT3_51	4
+
+/* flags show the minimum required OS to use a given feature. Currently
+	 only dwMajorVersion is used
+														MajorVersion	MinorVersion
+		Windows Server 2003					5							 2
+		Windows XP									5							 1
+		Windows 2000								5							 0
+		Windows NT 4.0							4							 0
+		Windows Me									4							90
+		Windows 98									4							10
+		Windows 95									4							 0
+		Windows NT 3.51							3							51
+*/
+
 const DriverDesc _video_driver_descs[] = {
-	{"null", "Null Video Driver",				&_null_video_driver,	0},
+	{"null", "Null Video Driver",				&_null_video_driver,		0},
 #if defined(WITH_SDL)
-	{"sdl", "SDL Video Driver",					&_sdl_video_driver,	1},
+	{"sdl", "SDL Video Driver",					&_sdl_video_driver,			1},
 #endif
-	{"win32", "Win32 GDI Video Driver",	&_win32_video_driver,	2},
+	{"win32", "Win32 GDI Video Driver",	&_win32_video_driver,		Windows_NT3_51},
 	{NULL}
 };
 
 const DriverDesc _sound_driver_descs[] = {
 	{"null", "Null Sound Driver",			&_null_sound_driver,	0},
 #if defined(WITH_SDL)
-	{"sdl", "SDL Sound Driver",				&_sdl_sound_driver,	1},
+	{"sdl", "SDL Sound Driver",				&_sdl_sound_driver,		1},
 #endif
-	{"win32", "Win32 WaveOut Driver",	&_win32_sound_driver,	2},
+	{"win32", "Win32 WaveOut Driver",	&_win32_sound_driver,	Windows_NT3_51},
 	{NULL}
 };
 
 const DriverDesc _music_driver_descs[] = {
-	{"null", "Null Music Driver",		&_null_music_driver,	0},
+	{"null", "Null Music Driver",		&_null_music_driver,				0},
 #ifdef WIN32_ENABLE_DIRECTMUSIC_SUPPORT
-	{"dmusic", "DirectMusic MIDI Driver",	&_dmusic_midi_driver,	1},
+	{"dmusic", "DirectMusic MIDI Driver",	&_dmusic_midi_driver,	Windows_2000},
 #endif
-	{"win32", "Win32 MIDI Driver",	&_win32_music_driver,	2},
+	// Win32 MIDI driver has higher priority then DMusic, so this one is chosen
+	{"win32", "Win32 MIDI Driver",	&_win32_music_driver,				Windows_NT3_51},
 	{NULL}
 };
 
+byte GetOSVersion()
+{
+	OSVERSIONINFO osvi;
+
+	ZeroMemory(&osvi, sizeof(OSVERSIONINFO));
+	osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
+
+	if (GetVersionEx(&osvi)) {
+		DEBUG(misc, 2) ("Windows Version is %d", osvi.dwMajorVersion);
+		return (byte)osvi.dwMajorVersion;
+	}
+
+	// GetVersionEx failed, but we can safely assume at least Win95/WinNT3.51 is used
+	DEBUG(misc, 0) ("Windows version retrieval failed, defaulting to level 4");
+	return Windows_NT3_51;
+}
+
 bool FileExists(const char *filename)
 {
 	HANDLE hand = CreateFile(filename, 0, 0, NULL, OPEN_EXISTING, 0, NULL);