I have a MacBook Pro that I purchased in November of 2007. I am currently running Lion. I had to take it in to the Apple store a few months ago to have them wipe the hard drive and re-install the operating system for me because it was running slow and I was getting the spinning ball all the time. My question is this. Is it a good idea for me to install ML? I know that often times, each release of a new OS, is more memory intensive than the previous version. If my machine already runs slow, does that mean that upgrading to Mountain Lion will just make it worse? Has anyone already installed it on a similar MBP who can tell me how their machine is running since the upgrade?? Thanks!