Everything should install perfectly and work OK till you try to Activate the Product. If this is happening you have the ability to ring M$ and not activate over the Internet and talk to a person and tell them what has happened. At that point they should issue you a new Activation Key which you have to type in and press Finish and make sure that the Activation has taken before you hang up.
Provided it's only a HDD failure that is involved here M$ should issue you a new Activation Key but remember that the Generated Key will tell them exactly what hardware is involved and when it was installed. You should have 30 days to activate the product from the day that you first install it.
Col