[ddouglass]

If you only have Hoster on one computer then you can install it on the back-up computer. To install use your original registration code and the email address that you ordered it under. This will be on you account order for it.
If you want to change your email address to the new one then log in to your account and go to your profile to change it. This will allow using the new one for installs from that point on. Be sure you have changed the one for the forums to the new one also.