What do you want the laptop to actually do?
If you have the power supply and the laptop, then it will work just fine. Play solitaire all you want. Watch a DVD (assuming the laptop has a DVD drive). Play mp3s on the laptop.
Here's the Newbie FAQ to help you figure out what you want and how to pull it off: New to CarPCs? Don't know where to start?
And here is the FAQ Emporum, a subforum with nothing but informational threads: http://www.mp3car.com/vbulletin/the-faq-emporium/
Nobody can hlp you if you don't know what you want to accomplish.