Do I need to de-activate HF on my old computer before installing on the new one?
Nope. My HF2 Express and Ultimate and my Hitfilm Pro are all installed on the same machine, and updates cheerfully install over existing versions.
With you HitFilm 3 come 3 activations you can simultaneously use. If you've used them up you have to deactivate HitFilm on a machine you don't use it on anymore, otherwise you can leave it activated just in case.
Oops, good thing Robin came along because I misread the initial question. Yeah, you get three installs, so go ahead and leave it on your old machine for now. Also, you can deactivate an install from your profile on this site, so (hypothetically), if your comp had a catastrophic failure--say the drive fried--your install isn't locked on the dead machine.
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