After posting this that is what I have started looking into. I found out that there are a couple of ways I could get a great audio signal to processors that accept coaxil or optical inputs. Possible options were a mother board with Optical out built in, a PCI Sound card or a USB/Firewire soundcard.
The MSI board was going to be too much for me. The board has an optical out and VGA, but was also going to require something like an Opus 320W to power it all I knew a guy that could get me a pretty stellar price with dual 2.1GHz processors and that alone was about the cost of the entire car pc I was looking for. This option was too pricey for me but could be a great start for someone looking to make an extremely fast and great sound carputer
A PCI seemed most logical but getting one to fit and look good in a Mini ATX case would be tough. I looked at some M-audio boards but decided integrating it into the case wasn't worth the trouble.
Guess this is really answering my own question but I wanted to put the information out there for others as well
This brought me the USB/Firewire option. Looking again at M-Audio i found the Fast Track Pro. It has coaxil and RCA outputs, which I will get good use out of with my current amplifiers. It also has an amped headphone output which will work out great for all those times I'm without audio because I'm changing something.

or for road trips when the passenger is asleep.