I have several RHEL3 WS machines that were installed here running as servers and their RHN subscriptions were never kept up. Now that I have become responsible for them I would like to move them to CentOS as I can keep them updated as needed. Some of them I can simply migrate to new machines, but a few I can not. Is it possible to simply upgrade a RHEL3 to the latest CentOS 3? If possible, once I have it to the latest Cent 3 can I then further upgrade the machine to the latest CentOS 4? -Thank you