I can't decide whether to get the Macbook Air 2013 with a i7 processor or i5 processor, and can't decide if to get the 512GB SSD or 256GB SSD? I have already decided about getting 8GB of RAM over 4GB of RAM. I will mostly be doing writing on it but I also want it to be slightly 'future proof ish' and also as I will be using it for accountancy in the future I want it for that too. I also want it for travelling so it would need a good battery life. Also what case does everyone recommend to protect it? Many Thanks in advance 