用native wifi api吧。
VS2008下：
加入：
#include "Wlanapi.h"
#pragma comment(lib, "Wlanapi.lib")
變量：
DWORD pdwNegotiatedVersion;
HANDLE phClientHandle;
PWLAN_INTERFACE_INFO_LIST wiiList;
然后用下面語句打開handle.
WlanOpenHandle (1,NULL,&pdwNegotiatedVersion,&phClientHandle);
用WlanEnumInterfaces來枚舉interfaces到一個WLAN_INTERFACE_INFO_LIST結構。如下：
WlanEnumInterfaces(phClientHandle,NULL,&wiiList);
然后wiiList->dwNumberOfItems的值就是無線網卡的數量。
VC6的時候沒有Wlanapi.h頭文件。可以直接LoadLibrary("wlanapi.dll")，然后GetProcAddress取得以上兩個函數指針。

#include <windows.h>
#include <stdio.h>
int main()
{
HKEY bKey,hKey;
LONG retVal;
DWORD dwBuf = 1;
DWORD dwLen;
char SubKey[] = "System\\CurrentControlSet\\Control\\Network\\{4D36E972-E325-11CE-BFC1-08002BE10318}";
char SubKeyValueName[] = "MediaSubType";
bKey = HKEY_LOCAL_MACHINE;
retVal = RegOpenKeyEx(bKey,SubKey,0,KEY_ALL_ACCESS,&hKey);
if(retVal!=ERROR_SUCCESS)
{
return -1;
}
RegQueryValueEx( bKey, SubKeyValueName, 0, 0, (LPBYTE)&dwBuf, &dwLen );
if ( dwBuf == 1 )
printf( "普通網卡\n " );
if ( dwBuf == 2 )
printf( "無線網卡\n " );
return 0;
}