As I said it earlier, if your app can bitstream dolby digital via spdif, then you have 5.1.
So if you have a dvd burner and windvd, it will send 5.1 via spdif.
If you have netflix app, it will send 5.1 via spdif.
If you have vlc (or whatever open source video player), you can force it to bitstream 5.1.