I just installed windows 7 into my brand new PC that I built and it says the product key is invalid. I typed it it word for word. My mom used it for her computer so does that mean the key can only be used once? Please help
That's what a product key is. A one time use deal.
The only type of product key that can be used multiple times is a Volume License Key.
You can re-use keys as long as there is only one active machine using it.
There is my moms laptop. It still says error
If its a OEM copy its tied to the original computer's motherboard...however if you whant to use it on a differnt computer you can ring microsoft and tell them you replaced your motherboard as your old one broke and thay will reactivate that OEM key for the computer it currently installed on over the phone.
I thought retail copies were 3 uses?
I bought a builders version of windows 7 on amazon home premium. Will that work for a clean install on my computer.
Nope.
Strange I thought retail was infinite as long as it's only installed on one system at a time.
use a windows loader?