MS Exchange 5.5

I have an exchange server running on a NT4 machine. This machine needs some cleanup. I want to rebuild this machine from scratch and install Win2000 Server, which include formatting the drives also. Now I need to setup exchange on another machine without loosing any of the current data/mailboxes/public folders etc. Then when I finish rebuilding the current exchange box I would like to move exchange on that again.
Prompt reply on this would be appreciated

Thank You