Confused as Hell.........

[Guydowood]

OK, I'm just another non-audiophobe without a clue as to what I may be doing wrong with my set-up and perhaps some off you that are surround sound savy can walk me through so I can get the best home entertainment experience, and for those that help, thank you in advance.

this is my set-up:

Hitachi 57' rear projection HD-TV, that has only 1 HDMI.
additional 5 channel componets and 2 S-Video

Magnavox NB500MG9 Blu-Ray player with these hook-ups:

HDMI
Component Y, Pr/Cr, Pb/Cb
Video out
L/R audio out
Coaxial

Direct-TV HD/DVR reciever

Onkyo HTS-6100 7.1 System.

Now, I got the 5.1 surround working properly for the Direct-TV-DVR set-up.
However, when I put in a blu-ray movie, I'm only getting 2.1 sound. Sound is coming through the Right & Left front speakers. Nothing for the center/sides or rear. I have the BD player plugged into multichannel, using audio component on the reciever. My HDMI is running from the BD to the TV. for visual. I understand the not all BD titles are in 7.1, but I've read that you can spread the sound out to achieve this or is that urban legend? Also to achieve full 7.1, do I need a multichannel BD player? Otherwise how do I get the 5.1 sound back for watching movies?

also, my old Sony system I was using an HDMI switcher do to the lack of HDMI hook-ups, do I still need to use this since my TV only has one hook-up?