My computer never came with an install cd, now the Windows key does not work.

OK, so I bought a used laptop from a sale from a major corporation. It came with a legitimate activation key for XP Pro. So I needed to do a reinstall, and since I do not have the disk, I used anther one. It won't exept the legitimate product key so now I'm stuck using a illegal one...I don't know what to do? How do I switch over, it won't take the key?

 

I don't know what's going on, but I'm using an illegal product key and it just passed Windows Genuine Advantage...so maybe I should just keep it?

 

Sorry. We can't be of any assistance with this problem for reasons that should be obvious.