Simplest and easiest way to go about this is to do a kife edge cutover.
1. Install same version of BES as your current BES on new hardware. Let the BES installation create a new DB instance on the new hardware. Do not point to the old DB. Make sure that the BES server name is the same as the current BES name.
2. Don't start the services on the new BES.
3. Backup the old DB and restore it to the new server
4. Install the latest SP on the new server which will update your DB schema. Make sure not to start the services.
5. If all goes well, Stop the services on the old server and then start the services on the new server. Disable the services on the old server so that they don't start up while the new server is active.
6. Wait and check the logs to make sure there are no problems.
You shouldn't need to reactivate any of the handhelds with this method.
Exchange 2003 SP1