I'm hoping to get the new Macbook Air but I'm torn in the decision of getting the 4gb or the 8gb of RAM. I'm going to use this MBA as my primary laptop for doing school work, presentations, skyping, browsing with a minimum of 10 tabs while streaming youtube videos at 720p or 1080p, playing some games occasionally like C.O.D, playing some Facebook games while playing music, watching downloaded movies. Yeah that's what I normally do. I want to play games while listening to streamed music from youtube. I hardly ever edit any photos or vidoes. Can I get the 8gb of RAM version in Apple Retailers or do I need to order it online? Does the 8gb or RAM reduce the battery life?