No, there are numerous changes in the code between RC2 and the final RTM
release. So I would suggest you do a clean installation of Vista RTM and use
your RTM key.
You may install and use the edition you chose for 30 days
without a product key. Simply click 'next' at the product key
prompt during setup, continue on and choose
the appropriate edition from the list.
You will be able to enter your product key at
the activation prompt at a later time.