win7:

hHook = SetWindowsHookEx(WH_KEYBOARD_LL, KeyBoardHookProcedure, IntPtr.Zero, 0);

XP:

hHook = SetWindowsHookEx(WH_KEYBOARD_LL, KeyBoardHookProcedure, Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0);

可以先执行win7的语句，如果返回的hHook是0，就再执行一次XP的方法。