Just entered the MacBook world and couldn't be happier with my machine's performance. I got the mid-2010 version (I'm a writer, so I don't need anything too high tech), but I have a couple questions. First, this MacBook is running Snow Leopard. I know that is now a fairly old OS. Which one, if any, should I upgrade to? I've heard some stories about speed and performance being hampered by downloading Mountain Lion. Also, I don't have Microsoft Office. Clearly I need that since I'm a writer. Where is the cheapest place to get it? Thanks, all.