Pro Logic II vs. Dolby Digital 5.1

[ender2009]

Hi! I have an old receiver that uses Dolby Pro Logic II technology. From what I've gathered, Dolby Pro Logic II is a technology that converts stereo sound into 5 channels to "simulate" surround sound. It does this when I play back music.

However, if I am playing a blu-ray that is uses a Dolby Digital 5.1 track, or some other form of Dolby Surround, then what is being played? Is it real surround sound? Obviously it's not a stereo source anymore, and it sounds like "real" surround sound to me.

I'm using a Phat PS3 with an optical cable.