BOOLEAN
    SetupDiClassNameFromGuid(
        IN LPGUID  ClassGuid,
        OUT PTSTR  ClassName,
        IN DWORD  ClassNameSize,
        OUT PDWORD  RequiredSize    /* optional */
        );
SetupDiClassNameFromGuid retrieves the class name associated with the class GUID.
The function returns TRUE if it is successful. Otherwise it returns FALSE and the logged error can be retrieved with a call to GetLastError.