I got an old laptop, could I use that in my car, is it possible to detach the laptop screen and use one made for cars and have the laptop in the glove box?
yes it is possible. The FAQ should be helpful to you.
Fusion Brain Version 6 Released!
1.9in x 2.9in -- 47mm x 73mm
30 Digital Outputs -- Directly drive a relay
15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
Buy now in the MP3Car.com Store
I say if you want to go cheap, you can always go the route I did. I just used a PC I got for free. It was a 700MHz Duron. It had a sound card and booted and ran RR. Added an inverter and I was good to go. That was a long time ago. I've since upgraded the PC and built a custom MDF case for it. The case can be made for next to nothing. Also, it doesn't have to be ghetto, and it can work. It's just generally easier and takes less space to use a DC-DC power supply.
If you're just getting started, using a freebie old computer and an inverter can be a great, cheap way to get started. Then, as time goes by, add or upgrade to your liking.