Mac Pro will not boot - HD and Machine are fine.

Greetings, and thank you in advance for your wisdom.

I have a 12-core Mac Pro, and she has been running like a dream. Once a month I run Onyx. Yesterday I did the same and upon reboot I got the grey apple screen and the spinning progress wheel that never stops spinning.

1. I repaired the HD via Disk Utility. All is fine.

2. The contents of the start-up drive are accessible - so the drive itself is not physically damaged.

3. I installed a new HD and made a copy of this Start-up disk via the Disk Utility. It will not boot from this drive as well.

4. I installed Snow Leopard (still using this) on the new drive to make sure the computer was happy. It fires up fine.

5. Everything is disconnected from the Mac Pro

So, I have obvious, and idiotically damaged the start-up disk using Onyx (assumption).

My life would be much better knowing I could do something that would enable me to boot from my current start-up and that's where I seek your wisdom.

Another question would be: If the above is not possible, if I install a fresh OS on the new drive, and then begin to replace all of the folders from the old drive (applications, library, etc.) will I be able to access my files as I did before. My issue is that I use this for music production, and there are literally close to 100 plugins that all have been registered. Going back through that process again would be days of labor, as some of these were purchases years ago. Tracking down serials would be a task. I think you understand.

So any advice that might prevent me from having to do as I said above will be wonderful.

Thank you all so much.

Lance