Quote: Originally Posted by
Bugbyte 
Find out how many watts your computer consumes and get an inverter that gives you at least 20% more than that. The information should be on the back of the computer.
The screen can be powered from 12 volt source unless it is a desktop unit.
I'm sensing I was not helpful enough to you. Here is more information on how to select a power supply for your computer:
Power supplies
explained.
General information on picking a power supply.