Как узнать что в системе появилось новое USB

#include <windows.h>
#include <dbt.h>
#include <strsafe.h>
#pragma comment(lib, "user32.lib")

void Main_OnDeviceChange (HWND hwnd, WPARAM wParam, LPARAM lParam);
char FirstDriveFromMask (ULONG unitmask);  //prototype

/*------------------------------------------------------------------
   Main_OnDeviceChange (hwnd, wParam, lParam)

   Description
      Handles WM_DEVICECHANGE messages sent to the application's
      top-level window.
--------------------------------------------------------------------*/

void Main_OnDeviceChange (HWND hwnd, WPARAM wParam, LPARAM lParam)
{
   PDEV_BROADCAST_HDR lpdb = (PDEV_BROADCAST_HDR)lParam;
   char szMsg[80];

   switch(wParam)
   {
      case DBT_DEVICEARRIVAL:
         // Check whether a CD or DVD was inserted into a drive.
         if (lpdb -> dbch_devicetype == DBT_DEVTYP_VOLUME)
         {
            PDEV_BROADCAST_VOLUME lpdbv = (PDEV_BROADCAST_VOLUME)lpdb;

            if (lpdbv -> dbcv_flags & DBTF_MEDIA)
            {
               StringCchPrintf (szMsg, 80, "Drive %c: Media has arrived.\n",
                         FirstDriveFromMask(lpdbv ->dbcv_unitmask));

               MessageBox (hwnd, szMsg, "WM_DEVICECHANGE", MB_OK);
            }
         }
         break;

      case DBT_DEVICEREMOVECOMPLETE:
         // Check whether a CD or DVD was removed from a drive.
         if (lpdb -> dbch_devicetype == DBT_DEVTYP_VOLUME)
         {
            PDEV_BROADCAST_VOLUME lpdbv = (PDEV_BROADCAST_VOLUME)lpdb;

            if (lpdbv -> dbcv_flags & DBTF_MEDIA)
            {
               StringCchPrintf (szMsg, 80, "Drive %c: Media was removed.\n",
                         FirstDriveFromMask(lpdbv ->dbcv_unitmask));

               MessageBox (hwnd, szMsg, "WM_DEVICECHANGE", MB_OK);
            }
         }
         break;

      default:
           /*
              Process other WM_DEVICECHANGE notifications for other 
              devices or reasons.
           */ 
            ;
   }
}

/*------------------------------------------------------------------
   FirstDriveFromMask (unitmask)

   Description
     Finds the first valid drive letter from a mask of drive letters.
     The mask must be in the format bit 0 = A, bit 1 = B, bit 2 = C, 
     and so on. A valid drive letter is defined when the 
     corresponding bit is set to 1.

   Returns the first drive letter that was found.
--------------------------------------------------------------------*/

char FirstDriveFromMask (ULONG unitmask)
{
   char i;

   for (i = 0; i < 26; ++i)
   {
      if (unitmask & 0x1)
         break;
      unitmask = unitmask >> 1;
   }

   return (i + 'A');
}