I have physical (DVD) media for snow leopard, which means that anytime in the future (say, 20 years from now) I could pop it into my old mac pro and reinstall snow leopard from scratch. However, it would be the unpatched, non-updated SL from 2009 when I bought the computer. How could I apply the updates that apple published between 2009-2013 ? Do the updates exist as files somewhere that I can download ? How can you apply OSX updates if they are not available from apple.com or through "software update" ? Thanks.