This is a pretty straight forward procedure and I will explain it to you 
below. I first want to point out a few things wrong with the code.

1.) There is no way to get those logged messages. I compensated for that 
    by making 3 changes which I will explain below after the windows 
    stuff. I am planning on sometime for adding the capability of the 
    messages being sent to the window in a list box or something similar in 
    the future. If you like let me know and I can keep you updated.

2.) Although I tried to maintain the cross platform issue I don't have 
    Unix so I am not sure if it still is. Let me know if you do have Unix 
    and compiler after making the changes (Thanks :)

Let's start then...

*** Open your comm.c file and cut and paste this section between the
*** START and STOP markers above your main() function:

START===============================================

#ifdef CIRCLE_WINDOWS
/*
** function prototype of main()
*/
int main(int argc, char **argv);

/*
** Windows global variables
*/
HWND hWnd;	  /* Here for future use in expanded Windows capabilities */
HINSTANCE hInst;  /* and used in InitWindow */
int CmdShow;      /* " */
/*
** CircleMudProc to run under windows
*/
LRESULT CALLBACK _export CircleMudProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
	switch(msg)
	{
		case WM_CLOSE:
		/* Window is closing and we send a WM_DESTROY Message */
			DestroyWindow(hwnd);
			break;
		case WM_QUERYENDSESSION:
		/* Windows wants to know if it can end and close us */
			return ((long) TRUE);
		case WM_ENDSESSION:
		/* All apps agreed to being closed so this it! */
		/* We don't even get a WM_DESTROY Message here */
			if(wParam)
				circle_shutdown = 1;
			break;
		case WM_DESTROY:
		/* We are destroying the window and closing the app */
			circle_shutdown = 1;
			PostQuitMessage(0);
			break;
		default:
			return (DefWindowProc(hwnd, msg, wParam, lParam));
	}
	return (0L);
}

/*
** InitWindow
*/
void InitWindow(void)
{
	/*
	** Init the Window stuff here...
	*/
	WNDCLASS wcCircleMudClass;

	/* Define the window class for this application. */
	wcCircleMudClass.lpszClassName	= "CircleMud";
	wcCircleMudClass.hInstance	= hInst;
	wcCircleMudClass.lpfnWndProc	= CircleMudProc;
	wcCircleMudClass.hCursor	= LoadCursor(NULL, IDC_ARROW);
	wcCircleMudClass.hIcon		= 0;
	wcCircleMudClass.lpszMenuName	= (LPSTR) NULL;
	wcCircleMudClass.hbrBackground	= GetStockObject(WHITE_BRUSH);
	wcCircleMudClass.style		= CS_HREDRAW | CS_VREDRAW;
	wcCircleMudClass.cbClsExtra	= 0;
	wcCircleMudClass.cbWndExtra	= 0;

	/* Register the class */
	if(RegisterClass(&wcCircleMudClass) == 0)
	{
		MessageBox(0, "Could not register Window", "CircleMud", MB_ICONHAND|MB_OK);
		exit(1);
	}

	/* Create Applications Main Window */
	hWnd = CreateWindow(
				"CircleMud",
				"CircleMud 3.0 Win95/NT Server",
				WS_BORDER | WS_CAPTION | WS_SYSMENU | WS_MINIMIZEBOX,
				0,
				0,
				200,
				100,
				NULL,
				NULL,
				hInst,
				NULL
	);

	ShowWindow(hWnd, CmdShow);
}

/*
** WinMain for Windows
*/
#pragma argsused
int PASCAL WinMain(HINSTANCE hInstance, HINSTANCE hPrev, LPSTR lpCmdLine, int nCmdShow)
{
	int argc = 1;	/* for the parsing and call of main. */
	int i;
	char** argv; /* used in parsing and call of main. */

	hInst = hInstance;
	CmdShow = nCmdShow;
	/*
	** Parse the command line and feed it to the main
	** function to take over
	*/
	if(strcmp(lpCmdLine, ""))
	{
		/* Find out the number of tokens in the string */
		for(i = 0; i < strlen(lpCmdLine); i++)
		{
			if(lpCmdLine[i] == ' ')
				argc++;
		}
		argc++;	/* the last token in the string won't have a
			   trailing space. */

		/* allocate memory */
		argv = malloc(argc + 1);

		/* fill the array */
		argv[0] = "circle.exe";		/* program file name */
		argv[1] = strtok(lpCmdLine, " "); /* get the first token */

		for(i = 2; i < argc; i++)
			argv[i] = strtok(NULL, " "); /* pull out any others */

		/* finish the array off. */
		argv[argc + 1] = '\0';
	}
	else
	{
		/* allocate the memory */
		argv = malloc(2);

		/* fill the array */
		argv[0] = "circle.exe";	/* the progam file name */
		argv[1] = '\0';		/* terminate the struct */
	}

	/*
	** Call the main function with the parsed command line parameters
	*/
	main(argc, argv);

	/* free the memory allocated for cmdline parameters */
	free(argv);
	return 0;
}
#endif

STOP==================================================

Add this section above game_loop()

START=================================================

/*
** wait_for_connection
** Used for windows or defined when compiled for non-unix
*/ 
#ifdef CIRCLE_WINDOWS
long wait_for_connection(int mother_desc, fd_set* input_set)
{
	struct timeval wait;
	long err;
	MSG msg;

	wait.tv_sec = 0;
	wait.tv_usec = 10;

	do {
		if(circle_shutdown)
			return 0;

		FD_ZERO(input_set);
		FD_SET(mother_desc, input_set);

		err = select(mother_desc + 1, input_set, (fd_set *) 0, (fd_set *) 0, &wait);

		if(PeekMessage(&msg, NULL, NULL, NULL, PM_REMOVE))
		{
			if(msg.message == WM_QUIT)
				return 0;
			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}
	} while(err == 0);
	return err;
}
#else
#define wait_for_connection(md, is) select(md + 1, &is, (fd_set *) 0, (fd_set *) 0, NULL)
#endif

STOP===================================================

*** Add as the first thing in game_loop.

#ifdef CIRCLE_WINDOWS
  MSG msg;
#endif


*** Add immediately after gettimeofday in the same function before the while 
*** statement:

#ifdef CIRCLE_WINDOWS
  InitWindow();
#endif

*** Add immediatly after the while statement

#ifdef CIRCLE_WINDOWS
	 /*
	 ** Give Windows priority over circle mud...
	 ** Why? I don't know. Move it if you want.
	 */
	 if(PeekMessage(&msg, NULL, NULL, NULL, PM_REMOVE))
	 {
		if(msg.message == WM_QUIT)
			break;

		TranslateMessage(&msg);
		DispatchMessage(&msg);
	 }
#endif

*** About 5 lines below that change

if (select(mother_desc, &input_set, (fd_set *) 0, (fd_set *) 0, NULL) < 0) {

*** to

if (wait_for_connection(mother_desc, &input_set) < 0) {


*** Now you are done that takes care of the windows portion.  If you 
*** want to make it so the log messages are stored in a file do this.

*** In your conf.h file add a define.  I used:

#define LOG_TO_FILE

*** Then in utils.c, add this above the log() function:

#ifdef LOG_TO_FILE
FILE* logfp;
#endif

*** And in the log() function change:

fprintf(stderr, "%-19.19s :: %s\n", tmstr, str);

*** to

#ifdef LOG_TO_FILE
  fprintf(logfp, "%-19.19s :: %s\n", tmstr, str);
#else
  fprintf(stderr, "%-19.19s :: %s\n", tmstr, str);
#endif

*** In comm.c, add this after your extern variables at the top of the file:

#ifdef LOG_TO_FILE
   extern FILE *logfp;
#endif

*** Add something similar to this in your main function after the variables 
*** are declared:

#ifdef LOG_TO_FILE
	logfp = fopen("circle.log", "a+");

	if(logfp == NULL)
		exit(1);
#endif

*** Add this to the end of your main function:

#ifdef LOG_TO_FILE
	fclose(logfp);
#endif