I'm just about to purchase a 15" Macbook Pro, early 2008. It is being sold with the 10.5 installation discs but the owner had officially upgraded it to 10.7 now. So, once I purchase it, how do I start off on a clean state, have my own user info, have my own home directory name and still use Lion? In other words, once I get the macbook pro, is my only choice to do the above, format the entire drive and install 10.5? And if I do that, would I still be able to upgrade to 10.6 and then 10.7 without paying anything? That is, would the upgrades be linked to the system serial number or to the original owner's mac account?