Reinstalling Windows on a Laptop

Hello all, I have to reinstall Windows on my girlfriend's mom's laptop because she has some weird virus....and I figured it would be just safer to nuke it all from orbit....  Just wondering if I uninstall Office first and provided I have the key, can it be reinstalled?  It didn't reinstall on a laptop I did a while least not with the key the guy gave me.

I believe that you can just enter the code when you go to install it again will have to call Microsoft (automated system) tell them that you have uninstalled it from your old computer and am trying to install it on a new computer. You will then enter the numbers provided on your computer then you will enter the code that they give you. Then office is activated. IDK which one that is for I think it works for 2007 and 2010. It takes about 5 mins.

You could also use some software tools to extract the code from the registry. You can save them and enter them again when you reinstall.