I'm sorry to start another thread about Snow Leopard but I haven't got an answer yet so here goes: I back up with time machine and would like to do a clean install of SL, would I be able to recover from my time machine even though it was backed up on Leopard and basically have the same machine b4 installing SL, i.e. colour profiles, safari bookmarks etc and if there are incompatible programs etc will they be installed and just won't run? One last question for the likes of aperture etc I have the retail version but will it back up with the key code so I won't have to type it in again, just curious? Also who else will be doing a clean install and restoring from time machine? What about this upgrade option I hear that is similar to archive and install, does it just rewrite parts the operating system while still running and applications stay intact? Is this an option you would recommend?