sound cards and audio setups are different for every user and car.
check out the 'adv. faq' link up at the top of the page for some generic info on connecting a computer to the car stereo.
OK guys, slowly pulling my Carputer together and was wondering what everyone is using as far as sound cards? How exactly are you connecting the output to the 8 speaker wires in the car? Do you still have control of left, right, front, rear fade/balance? I briefly looked in the MP3Car store but didn't really find anything. And I know the card on my laptop and desktop only have one or two outputs. Someone educate me =)