Install AU if you're using Logic/Garageband Install VST for other hosts or RTAS if your a
pro tools user.
Install Kontakt 4 first. Install Galaxy to wherever you fancy.
If Kontakt can't see it you can just browse to the Library add it via the Kontakt
interface and then Authorise it via Service Centre. 3rd Party Kontakt Libraries generally
don't care where they're installed as long as the drive is fast enough.
my last hardware Migration I just coped the Galaxy NKI and Samples folders across manually
and told Kontakt where they were.
Vintage D is a great Sample Piano I'm sure
you'll love it.