Would this act be illegal? Surely the data I created on my computer is my own intellectual property. If Micro$oft lock you out of your system then they deny you the right to your own property. Am I correct?

No, because no one is locking you out of the data on the hard drive. You just can't use that same drive to boot Windows Vista. The curious part is, why would you even be concerned with that? Surely you don't believe that it will lock you out all the time by accident, right?