I am not sure this is the smartest/fastest solution but here is how I would do it:
1) Stop the Orion services.
2) Connect to the database. Truncate the statistics tables to only keep your settings.
The tables that end with a _Detail, _Hourly, _Daily contain statistics but no settings.
The Traps, TrapVarbinds, Syslog tables can be truncated too.
Doing so should reduce enough the size of your database
You did not specify if you have any Orion modules installed so I listed only NPM tables.
3) Backup your DB, move it to the new server and restore it.
NPM Settings and statistics tables are in the same filegroup so it is not possible to backup only a specific file such as detailed in the following link: http://msdn.microsoft.com/en-us/library/ms179401.aspx