have an iMAC 10,1 which is supposed to be updatable through Mavericks. Previously had a network administrator, but this network system has been discontinued. So have Snow Leopard 10.6.3 now. When download even 10.6.4, the installer says that "this software is not supported on your system". Updater button itself does not work, saying there is a network problem, but trouble shooter says it is working fine (direct connect for internet service is fine). Any ideas? Thanks in advance.