我也来补充下，嘿嘿，调用这个函数就可以得到当前屏幕的显示参数了。。。
     cxScreen = GetSystemMetrics (SM_CXSCREEN) ;
     cyScreen = GetSystemMetrics (SM_CYSCREEN) ;

详细点
#include "windows.h"
#include "tchar.h"
#include "stdio.h"
int CDECL MessageBoxPrintf (TCHAR * szCaption, TCHAR * szFormat, ...)
{
     TCHAR   szBuffer [1024] ;
     va_list pArgList ;
          // The va_start macro (defined in STDARG.H) is usually equivalent to:
          // pArgList = (char *) &szFormat + sizeof (szFormat) ;
     va_start (pArgList, szFormat) ;
          // The last argument to wvsprintf points to the arguments
     _vsntprintf (szBuffer, sizeof (szBuffer) / sizeof (TCHAR),
                  szFormat, pArgList) ;
          // The va_end macro just zeroes out pArgList for no good reason
     va_end (pArgList) ;
     return MessageBox (NULL, szBuffer, szCaption, 0) ;
}
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
int cxScreen,cyScreen;
cxScreen = GetSystemMetrics (SM_CXSCREEN);
    cyScreen = GetSystemMetrics (SM_CYSCREEN);
     MessageBoxPrintf (TEXT ("ScrnSize"),TEXT ("The screen is %i pixels wide by %i pixels high."),cxScreen, cyScreen);
return 0;
}