I've read that earlier versions of OS X than Panther were a bit wonky, to varying extents. I've never seen any of them in action, but would like to try 'em, if only for fun. I've also read that certain updater CDs for earlier versions of OS X could, in fact, be used to install the updated version whole and entire (i.e. the updater CD was, absenting a few software tricks, an install CD for the higher version). Is this correct? If so, what's the Colonel's secret recipe? Academic interest, you know...