Install legal copy of win7 over a bad one

Hello. A friend of mine have a pc with invalid windows 7 installtion (I get a message that that I may be a victim and so on...).
I have a real original windows 7 pro copy that is still new and wasn't registered yet.

Can I register the bad copy with the key of the good one so it will be legal and she want need to reinstall windows 7 (because then she will need to install all the other programs she already install on it).

Thanks.

@ 1st I was going to say "No" but, actually it might. Try it, nothing to lose. Regards, Drew

My only concern would be where the original media came from. If it came as a download from Digital River, it should be good. If it came from eBay, my confidence in the whole transaction would be diminished. Because I've been burned twice. Fortunately, both times, eBay refunded me at my word only (counterfeit item), and on one of those, MS gave me a brand new XP Pro installation package, after sending them the counterfeit item. They told me that if it was "high grade", that I would get a replacement at no charge.

I didn't feel any guilt over turning the item over to MS for a possible new one after eBay openly refunded me, due to the trouble I want through, twice. A refund doesn't replace the PITA you get after seeing that black screen. Needless to say, I no longer buy software on eBay.

Through experience, I've learned what to buy & what to stay away from on eBay. If the price sounds too good to be true, that's because it usually is. This includes MS software keys. The keys may activate at first, but at some point, they often fail validation. Usually, when this happens, it's too late. eBay & PayPal has a 45 day protection plan, many times it's 3 or 4 months before the user gets burned. What gets me is, why do they validate in the first place?

Cat