I'm also interested in this too, if you use it as a media player to play your ripped dvd's can you still get 5.1?
Sorry dont know much about this at all.
Standard Dolby & DTS audio will decode from files fine, however the PS3 will only decode HD audio (TrueHD & DTS-HD/MA) if it's directly from a Blu-Ray disc.
if you use it to steam media, can you make it display artwork and film info etc?