Hello, I am planning to switch laptops with another person. My laptop being an early 2011 macbook pro that came shipped with snow leopard but which was eligible for the free lion upgrade (which I upgraded to) and the other person's being a mid-2012 model with mountain lion. I want to transfer my data to the next laptop and transfer the second's person's data to my laptop so I have already made backups of both laptops using Time Machine. I want to then format both laptops and load my data on her laptop and load her data on my laptop. So the whole problem now comes here. I have read that the OS is also erased from the laptops so I wanted to know if I could download the mountain lion for the second person's laptop even though I have no hardcopy or softcopy of the OS and whether I could download lion on my laptop even though it came shipped with snow leopard. I know this post was too long and somewhat complicated so I am ready to explain further if required. Any answers and suggestions are welcomed.