Wow!
It seems like a lot of money, time, and effort to go through just to make your own car stereo. Using a lot of open source linux software and an expensive Via mini-atx pc would not be my choice. I notice it took the guy years to do this.
My stereo in my truck has 180 watts, has an am/fm tuner, plays cd's, has a usb port for flash memory sticks, an auxiliary plug for my mp3 player, and a memory card port - and I bought it at a local Target store for less than $100.00.
For portable music storage, I've got a seagate 2.5 gig portable usb mini hard drive, a seagate 5 gig portable usb mini hard drive, a 1 gig memory card, an mp3 player that has 512 mb's of onboard memory plus a memory card slot built in that takes up to 1 gig memory cards, and a 1 gig usb flash memory stick.
And I also have an fm modulator adapter for my stereo that plugs into my cigarette lighter that will play music from a usb flash memory stick, portable mini hard drive, or an mp3 player.
But then I own a pc repair and sales business and I buy all of this stuff at cost..so I can afford all of that computer geeky stuff...lol