You can just copy the bb folder to a hard drive and run it from there or copy the bb folder to the new PC, along with the C:\Program Files\PG Music Inc
There are only a few things you need to install like bbfonts.exe, pgdx_plug_2_0_0.exe, biab_daw_plugin.exe (should be in C:\bb\Data\Installers), Sforzando and I think just one Library should register it ?
Run it and enter serial.
It should just update the Sforzando PG library, if you don't have all the Playable RealTracks in Sforzando copy the original Band-in-a-Box Sounds.bank.xml in the PG Music Inc folder.
The Audiophile version is over 1.5TB