I have no idea how great my setup could be....

After reading up and down these boards, I'm really searching for a way to get the most out of the hardware I have with spending little, if ANY, money. My specs are:

Asus P5Q Pro
Core 2 Quad 2.4GHz
4GB RAM
Sapphire HD 3870
Realtek ALC1200 onboard audio with an available Audigy Gamer card
Logitech Z-680 speakers with coax, optical, and analog cables available, pc currently connected via analog 6ch direct
Samsung LN46A650 46" 120Hz HDTV

Now, I just bought a DVI-HDMI cable to hook up my TV to my video card's other DVI output, but I'm really wanting to see how to get the best out of this setup.

I posted a thread yesterday about screen tearing with mkv's in all media players, but after installing reclock and an earlier version of VLC, that's almost completely solved in all media players. So my questions are:

1. Can MPC-HC really benefit me more to take me away from BS Player, which I love the interface of and unattached control panel?

2. How can I get the best audio output with any source onto those speakers??? I know most of the mkv's I have are encoded with DTS, so I'd like to know if I'm doing what i need to achieve that.

I've read about ffdshow and whatnot, but is that really needed to have DTS streamed from my PC since my speakers decode DTS?

Thank you for taking the time to give me your input!