To further clariy Gonk's comment,with Blu-Rays all soundtracks can also be decoded in Dolby 5.1 or DTS 5.1 streams using the accompanying digital outs (optical or coax) on the players.
Every single demo at trade shows has been conducted exclusively with Blu-Rays due to the superior picture available and delivering the decoded 5.1 sound is no problem at all.

Peter