I bought Snow Leopard a while back but was too busy to upgrade to it so I'm just doing it now. I'm a little confused... When I run the installation (it's running right now) will it automatically delete all my old files and clear out Leopard? Or do I have to do that myself? And if so how do I do that? The reason I ask is because when I clicked my HD to install it, it read "105gb free. Total 158gb" Thanks for any help!