I have a mid-2010 15" MPB that is currently running snow leopard. I am very interested in updating to mountain lion but I'm a little apprehensive because I don't know if my mbp will run slow with it. I have a 2.66 GHz Intel Core i7 processor and 4GB RAM and use the computer for school work like writing papers, watching movies and going on the internet. So would I benefit from getting 4 more RAM? And, if I do, do I need to get an 8gb module or can I add a 4gb one to the second RAM holder? Also, will adding the RAM do anything to the data info on my computer? Thanks so much for the help!!!