My HD went out on my MBP. When I got the MBP new 6 months ago, I also purchased Microsoft Office Student/Teacher Edition. There are 3 codes on the back of the box. The first one I used for my computer before the HD went out. The 2nd one was used for a different computer. I have a third unused code I could load on to my computer that has the new HD in it. My question is, do I need to use that 3rd code? If I do, does backing up my HD periodically also prevent me from purchasing Microsoft Office again if my HD goes out for some reason or I get my computer replaced under warranty?