Just a year after Lion (OS X 10.7), Mountain Lion (OS X 10.8) is here. And just like Lion, getting Mountain Lion is as easy as downloading an installer from the Mac App Store—a few clicks (and some patience) is all it takes to install OS X 10.8 over your existing copy of Lion or Snow Leopard. But that doesn’t mean you should make the jump without any preparation, or that there are no important decisions to make along the way.