That would depend on how you have it setup on the current one.
If everything is contained withing the Launchbox folder structure (media, roms, emulators) it is usually as simple as copy and pasting the Launchbox folder to the new pc.
If you have things stored on different drives or stored outside of Launchbox it would take a bit more work to make sure everything is linked since drive letters/names and folder paths could be different on the new pc..