Please correct me if I'm wrong, but the item you've linked to looks like a controller + interface (nice one at that) and nothing more.
Good to see you're going the 2-channel Music PC way!
I'm also a very hardware-challenged person, but after a bit of reading and research I managed to set up a Music PC. I simply chose and bought the components -- I got it assembled by somebody who knows what he's doing. You can read about it
here (shameless self-promotion, heh, heh).
You'll find the "Art of Building a Computer Transport" a very good place to start reading. You can download it from
here.
It will be a bit difficult to implement everything that's mentioned in that paper, but you can follow the general principles and rules, and suit the system to your particular needs.
These are other interesting resources:
The Well-Tempered Computer
Music computers - Gearslutz.com
Quiet PC Experts - Quiet PCs and Top Silent PC Parts
silentpcreview.com | Everything about Silent / Quiet Computers
Your priorities for the build will be silence in operation and quality of sound output. You will need to choose every component with these two aspects in mind. The cabinet, the PSU and the motherboard/processor's cooling fans & options, and the hard-disk will need to be paid special attention to. If you choose your components well, you can get by without any additional mods to any of the equipment.
Next you will need to choose how you will get the sound to the amplifier: internal soundcard or external DAC? Whatever you choose, you will have a plethora of options to choose from, esp. if you choose to use an external DAC. If you do choose to use an external DAC, you will need to choose how you will connect the PC to the DAC: USB/Optical/Coaxial.
On the software side, you will have to choose a media player software (CPlay or Foobar 2000 are IMHO the best), and make a choice on using the best way of bypassing the windows audio processing (ASIO/ASIO4all or WASAPI, depending on the operating system).
You will find most of the basic guidelines you'll need in the "Art of Building a Computer Transport".
It would be a good idea to decide how much you want to spend on the PC (plus a DAC if you choose that way) first. Then you should settle on the sound card vs. DAC question. (Well, the first and second decisions kind of run into each other, don't they?). Most of the other things will slowly fall into place