To spicystick,
Leave the PS3's output on LPCM on the maximum bitrate settings the Integra will allow. You can let the PS3 do it automatically during the audio setup wizard and it will show a list with compatible rates already checked off for you.
Go into the Integra's speaker setup menu, if you have not done so already and select "NO" instead of large/small for speakers you do not have hooked up.
Now when you listen to games and movies, I am thinking depending on the listening mode, the Integra should automatically redirect any surround info to your existing front speakers.