Hi, welcome to MP3car.com.
It's all very possible. My CarPC does way more than that.
But seems like you wanna go cheap or skimp out on some parts.
You will want some type of Navi eventually most likely.
But for now, get your self a shutdown controller and pick up the mp3+ usb soundcard. You can get both for under 100 buks together.
I would use XP.
Start building and search here or ask questions for help.
BTW, you boostin any extra in your Turbo AWD GSX? -interface your pc into the cars ecu and you can hit 12's with that car.