Allow me to suggest running the VGA and Audio (if needed) through PCI. The rest (WiFi, TV-FM, Touchscreen, GPS, etc.) should be USB devices. As far as I can see, the best benefit of running USB devices is that they become more mobile and don't have to be attached right on, or next to your carputer.
To be honest, I've never heard of a USB VGA device. Also, most MoBo's have built in Audio which saves you a PCI card.
Finally, leave your serial ports open... Somebody on this website is building an Air-Cond. controller that works via LPT. Keep in mind that many people connect their GPS receivers to their COM1 port (to eliminate problems after hibernation).