Stupid Question DVD-A on my computer or What am I listening to?

I just got a new computer with a dvd-player. When I am listening to a DVA-Audio i.e Rumours or A Night at the Opera... what am I really listening to from an audiophile perspective?

I am listening to the two channel track dts or Dolby digital. I realize I am not getting the full benefit of the DVD-A format, but I am really impressed with the sound. Should I be? Is the resolution higher than standard red book?

If I am strictly a two channel listener does DVD-Audio take me much further? I hope I am making sense.... Thanks .....steve c