Hello.
I just went from Bootcamp to Parallels.
I can't speak for AutoCad,
But I can speak for Adobe CS4.
Parallels installed easily and setting up my BootCamp drive to work as a virtual machine was easy enough...
But the process got a bit ugly.
First, Windows had to re-activate. No problem IF you have the "Full Retail Box" version of Windows. OEM versions of Windows are extremely likely to fail re-activation. The CD key itself shouldn't be needed.
Second, Adobe CS4 programs lost their activation.
Adobe has a "Deactivate" function that must be done before transferring activation to a different or virtual machine. I should have done that first. The CD Key was not needed.
So I re-booted from Boot Camp and de-activated CS4. Starting from Boot Camp caused Windows to damage the Parallels setup.
So then I had to start over again with another Parallels setup and re-do the virtual machine. Then I was able to re-activate CS4. Ugh.
I suspect that AutoCad will put you through the same nonsense.
Good Luck,
Keri