I have one unit of mail server running on windows nt4.0 and exchange 5.5. And i would like to upgrade it to Windows 2000 running on exchange 2000. So i want to minimize the server down time. So i think of setup another server install the nt4.0 with exchange 5.5 same setting as my current server and restore all my mail box. Then only down my current server. Due to the server is under slow performace so i decide to reformat it and install the windows 2000 server then install exchange 5.5 then restore the latest backup and only migrate to exchange 2000. Do you think is it a good or proper procedure ? Patrick