Need to upgrade a legacy rails app running in Rails 1.2.3 to a latest production stable version. There seems to a total revamp in the almost every aspect of rails since 1.2.3. Can this be achieved in a single step upgrade (1.2.3 to say 3.2.14 (if not 4.x)) or it has to be a step by step process (1.2.3 to 2.3.2 to 3.2.14 to 4.x). The app is currently running in Windows 2000 server with Mongrel clusters using Apache server. Any suggestion/comments will be highly appreciated.