codice:
BOOL QueryRegKey(const TCHAR* szPath,
                 const TCHAR* szKeyName,
                 CString& strValue)
{
    HKEY hKey;
    TCHAR szValue[128];
    LONG nValueSize = 128;
    DWORD dwError = RegOpenKey(HKEY_LOCAL_MACHINE, szPath, &hKey);
    if (ERROR_SUCCESS != dwError)
         return FALSE;
    RegQueryValue(hKey, szKeyName, szValue, &nValueSize);
    RegCloseKey(hKey);
    strValue = szValue;
    return TRUE;
}
naturalmente non è testato.