I have a Macbook Pro (Late 2007) 15-inch, running OS 10.6.8 Snow Leopard. What is the latest OS it is safe to install on my computer? Mavericks? Mountain Lion? Or Lion? Can I install any of these or will they ruin my computer? I have read many horror stories in reviews for each of these new operating systems, and maybe they wouldn't be safe to install for my older macbook pro.