I have been playing the demo unpatched on a dual core MacBook with Tiger 10.4.11 OSX. There have been no issues other than injuries etc. I would like to buy the game and continue my saved game from the demo but it is apparent from other threads that the full version will not work on Tiger with the new patch. Therefore I am considering upgrading to Leopard but would like to know if my saved demo game (played on Tiger) will work in Leopard (with a patch)? In other words, will a change in OS affect my saved game and/or the patch?