Upgrade question about OS

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1

I am planning on doing an upgrade soon and i was wondering: Wat all can u upgrade in your computer without having to buy a new copy of your OS (for non linux users), i currently think u can upgrade anything except for the motherboard cuz then it classifies as a new computer and your current windows install will not work.

Any answers r appreciated.

 

P,S, 

if i do u end up having to buy new OS, i have already decided not to get windows 8

 

I am not gonna post any of wat i am planning to upgrade because it is still in speculation, i want to see wat i can upgrade first.

2

You don't have to buy a new License. You just have to reactivate it.

3

If you have changed too much you may have to call MS. Get a pen and pad ready before the call becasue you are going to writting down some long ass number. There is a key question they ask they you have to get right. "how many computers is this copy of windows installed on" or something like that and of couse the answer is one.