changing from Rails1.2.5 to Rails2.1 and also to latest Ruby

I am using rails 1.2.5 for my application..Now the company has a
plan to shift to the latest version ..So could you please what ever
things to be noted ?My ruby version is 1.8.6 Also can I shift to rails
2.0.1 and Ruby 1.9.X (which I hear is more faster than current) Please
give me a good direction regarding this

ruby 1.9 is not yet production ready. It is hoped that 1.9.1 (the
first production ready version of the 1.9.x line ) will be out in
january (
Rails 2.0 isn't compatible with it either.