I'm trying to sell my old mac. It originally came with 10.5, but I currently have Mavericks on it and want to sell it with Mavericks, will just reinstalling wipe all of my data or do I have to erase the disk with disk utility first? If I do have to wipe it, does the restore disk still have 10.5 on it? Can I upgrade to 10.9 from 10.5? Thanks