I am not a Apple user, but I want to upgrade a MacBook 4,1 to Lion 10.7/10.7.5 but when I boot from the CD with the dmg file I bought from app store, I click on Reinstall Mac OS X but I get a message saying You can't upgrade this version of Max OS X. I think this happens because I did not format the partition prior to the installation but I want to make sure this is the reason, since if I format it and the setup wouldn't let me install Lion, I would be stuck without an OS.
I currently have 10.5.X installed and my Mac have 4GB of RAM as required for Lion.