I want a computer in my car is it this simple?

Here's the plan! Buy a PC (extra small). Get a DC to AC converter, Plug the PC up. Connect a small (touch screen) monitor, connect a wire from audio out to aux in on my pioneer head unit. that seems too easy, is this it? I got a 300 watt amp and sub too, will drawing that much power hurt my car? What about a laptop with a car charger if that first one wouldn't work?I want a computer in my car is it this simple?
As long has you have a good battery ( red top) or dry cell,and you dont run the systems to much while the car is off ( no more than 30 mins) you should be fine. Just start the car up ever 30 mins, let it run for bout 5 mins and it will charge battery back up. When you add the up the total watts your probably only looking at a total drain of maybe 1000 watts * about average amp size *.300 for cpu, 300 for audio system, and maybe 270 for your head unit.. The laptop and car charger route will work but i would rather run a 16 gauge wire from the battery, behind a fuse ,to a DC - AC converter. That way you can run from the battery not the cig lighter. That way you can pick the fuse size and not use the 20 or 30 amp fuse that runs behind the cig lighter. If you want to be safe you can run all of these behind a small capacitor.