Ok, I've got the PS3 hooked up via HDMI to my tv & via Optical Audio to the Bose. Now what I want to know is why the heck does the sound drastically vary when listening to a song in a game as compared to listening to the same song via the Bose CD player in the receiver?

It's like night & day. The Bose CD player sounds incredible and rattles the walls like mad...but the same sound coming from the PS3 sounds flat and much lower volume...it is supposed to sound exactly the same according to the Bose sales people. The settings are exactly the same in both cases. All I do is change the source from the CD player to the PS3. Why is there such a huge difference and how do I correct the problem?

I'll be getting a PS3 soon & have a few questions first.

1. If I have the chance to go for an 80 gig model or a 40 gig model, which one should I get? I still have & use my PS2 so backward compatibility is a non issue.
2. I assume the PS3 saves games to the hard drive? What am I supposed to do when the HDD is filled up? Do external HDD's work as good as the internal one?