Try contacting Steinburg about the authorization.
I know with Ableton, when trying to install it on my new computer, I "ran out" of authorizations during the authorization process, it came up with a field that basically sends an email to them with a reason for needing more authorizations.
Almost the next day, they sent me a reply saying I have 2 more. I just told them I changed hardware (i bought a custom PC that killed my old G4 in raw power).
If you have a legit COA for the software, taking a picture and sending them proof you own it may also help if your reasoning doesn't suffice, or they're a bit tougher on their policies (I've never used Cubase, so I'm not familiar with their customer support).
Furthermore, in terms of hardware, I've always been a fan of M-Audio. I used to have an Axiom49 that I used to control my software synths, act as a drum controller/sequencer, and could adjust parameters within my DAW. I'm also currently using an M-Audio firewire interface for my recordings (just simple home-stuff, nothing major yet).