I have an 11in Base Model Macbook Air from 2010, and am looking into a desktop. I already have a keyboard, mouse, and monitor. Im just looking for a good desktop that I can use as my main computer and just use my macbook air when I leave the house. My needs are; a big hard drive to store my large files, and a somewhat fast computer that I can use to edit my 5 minutes+ videos for youtube. What configuration would be right for me. By the way, my spending limit is $800-$900