A windows disc will install the exact information be it OEM or full product9except the evaluation offers). I have used many keys of OEM and retail variety. They all work if you haven't abused that key. And when you go to activate over the internet, if you get the message that it's no longer any good, activate it over the phone. They give you 8 groups of 6 digits each and ask you if this "is being used on one machine only". Tell them yes (be truthful) and that's it. They will ask you if this product has been activated before and be honest if it has. They will still activate it for you. I have used product keys as many as 8 or 9 times and never been refused, as long as I am honest with them. A few years ago, a friend who works for Dell sent me XP Pro with a 'volume license'. At that time I loaded it on several PC's and they (#1). Did not require activation. (#2). Passed the "genuine" validation. Now there are copies of "corporate edition" being sold on Craig's list etc. but I'm staying away from software being used illegally. You can swap any components and reactivate. Usually after a major hardware change, you need to use the phone activation and answer some questions regarding those changes. You can use one copy of each different program, it's the product key that identifies the activation part.The product I.D. number will not interfere.