MushinTech
You can do a backup to USB either using the server manager backup & restore panel to workstation (ie to a local USB or a workstation share) or from the admin console menu to a locally connected USB drive.
These backups will backup all user data & email, ibay data & configuration settings & databases, but they do not backup any contribs installed.
Contrib data will be backed up.
You then use that backup to restore to a freshly installed sme 8 OS on new hardware.
You then install any compatible contribs (ie sme 8 compatible el5 versions).
Read the Manual re backup, see link at top of Forums.
Also read this howto for general info about backup concepts, & specific details re how to do limited backups , but be warned you are on your own when you use non standard approaches to backup & restore. Read the whole howto.
http://wiki.contribs.org/Backup_server_config