Khurram Bhai, I am so happy to know that your car is going high-tech .... MashaAllah
I looked at the Revosys system. It looks good to me. Just make sure that you get card for 5.1 surround system. It will markedly improve your listening pleasure. Since, such systems are built with very small components, it would be difficult (perhaps impossible) to find components if you decide to change later.
I suggest that you also look at MP3Car.com - Recent Blogs Posts - Blogs and Mobile Computing Solutions - Innovations in Mini ITX for other options.
The Revosys has two USB ports at the back and one mini-USB at the front. Once you start using, you will realize that you need lot more USB ports .... Of course, it is possible to use USB hubs, but then all USB devices do not get 5 volts each current.
I suggest that you also consider separate CPU carputers. Perhaps the only problem with such CPUs is their location. Dashboard does not have enough space behind it to house as amplifier sized computer .. the MoCoSo system I have selected comes with 10 USB ports.
My best wishes ...