At Centrafuse, we only provide the software that runs on a WinXP/Vista/Win7 car computer. The hardware side is handled by our hardware partners. If you're a beginner, be sure to check out http://www.mp3car.com
as they have a huge forum and wealth of knowledge. Find the forum and read and then read some more.
Here is another great resource on the mp3car website: http://www.mp3car.com/content/150-car-pc-101.html They also have an online store with tons of niche CarPC hardware systems and accessories.
Another great hardware provider in the US is MCS (Mobile Computing Solutions) Visit their online store and check out their complete systems and CarPC accessories. - http://www.mo-co-so.com