<HDPC> Setup and Configuration Question

I'm currently in a pickle about what connects to what, how and why it connects, and what is optimal for me. It's probably a rookie kind of HTPC question, but it's first time around for me, only have to learn once right..

I have:

ASUS 26" HDMI LCD (ASUS VK266H 2ms Full HD DVI)

VGA Port(s) 1
DVI Port(s) 1
Video Input Component
Audio Input 3.5mm/RCA
Headphone Jack 1
HDMI 1

Nvidia GTX 285

DVI Port(s) 2
7-pin analog HDTV-out mini-din, and S-video connector, or YPrPb (component) or composite outputs.

ASUS Xonar HDAV 1.3 Deluxe

RCA jack *8
Analog Input Jack
Line-In/Mic-In 3.50mm mini jack *1
Other line-level analog input (for CD-IN/TV Tuner)
CD-In, Aux-In (4-pin header on the card)
Digital S/PDIF Output
Coaxial and High-bandwidth Optical Combo Connector
Supports 192KHz/24bit
Digital S/PDIF Input:
Coaxial and High-bandwidth Optical Combo Connector
Supports 192KHz/24bit (Shared with Line/Mic In)
HDMI Input/Outut:
HDMI1.3 – In/Out Type A *1

z5500 Speakers

Optical 1x Coax 1x Optical
Analog

My question is, how on earth should I go about connecting this all up?

Does HDMI replace my DVI, if so from where is it connected?

How is my GPU connected to the screen?

I don't mind buying more connectors if i don't have the necessary or best ones at the moment.

Anyways thanks in advance for any help... at the moment i just have my speakers connected via optical and analog to the Xonar, and switch depending on game/media, screen DVI to GPU I'm a tad lost whats next..