Well XP is a little more customizable then Mac, which is why people like them and hate Mac. The avg user needs a little more knowledge of computing as well.
With that, what player are your users using ? Media Player has never been a good player. VLC is what I use….and it’s free:). If your customers can’t figure out they Need or don’t know how to use your player, that’s not yours or Microsofts fault.
I’d simply direct them to a good software player