few questions about the audio from my 506

[tbizzle]

Ok, when I first set out to buy an audio setup for my HT, I had no idea what I was doing so I went to AVS for advice. I was looking to buy a cheap receiver for my new Polk R50's back then, and the Onkyo 506 was recommended to me. I got a refurb'd one for $160 shipped from Onkyo's site. Not bad just to get my new speakers up and running. But I later found out that the 506 can't decode HD audio, even though my PS3 does.

And I remembered reading blu-ray reviews of certain movies that had awesome sound quality, and thinking "hmm, I don't remember it sounding that good". Take for instance Iron Man or The Matrix movies, they always sounded weak to me on my setup, whereas movies like Live Free Or Die Hard, I Robot, Incredible Hulk, Flight of the Phoenix, etc. sound totally badass. So I looked up the Soundtracks on these movies and they all had DTS HD MA soundtracks, whereas the "weak" ones had Dolby TrueHD.

So I have 2 questions:

1. If I'm not actually hearing these HD soundtracks due to my receiver, what am I hearing? Just a regular Dolby 5.1 like on a DVD?

2. When I get a new receiver, such as Onkyo 805, etc, will I notice a huge difference in the TrueHD sound, since it will be HD instead of whatever I'm hearing now?

Sorry if some of what said is wrong or doesn't make sense, I'm still an audio newb trying to learn. Thanks in advance for any help