Which is better Auto Sound Calibration or Dolby Pro Logic II for speakers?

The Speakers I have are Samsung HT-C555 and i have a wireless unit for the rear speakers. But in the manual they say that if you use the ASC(auto sound calibrate) function for your speakers then the Dolby Pro Logic II wouldn't work. I was wondering if i keep the ASC function then would the sound effects still be as good as Dolby(cinema mode) or is Dolby better. Another Question is what is the best place for the rear speakers. Thanks alot.