Question how to hook up the speakers for my HTPC

[bail_w]

I have

42pz77u 42" 1080P HDTV
Logitech Z-5500 Speakers
Direct TV receiver
HTPC with sound card

my questions is how should i hook the speakers to get the best sound quality? with Digital Coaxial Audio RCA Cable? or what do you recommends? Thanks

edit: this is how the back of the tv looks like.

 

[w1retap]

Use the PC to go analog to the z5500's
Use digital from the DirecTV box to the z5500's
Video should go via HDMI/DVI to your TV from both the HTPC and DirecTV box.

 

[bail_w]

Use the PC to go analog to the z5500's
Use digital from the DirecTV box to the z5500's
Video should go via HDMI/DVI to your TV from both the HTPC and DirecTV box.

thanks.