Hello soon i am going to upgrade to a new pc and i wanted to know if i can use the cd key for my current computer to activate windows also i want to know if i reinstall windows 10 and put it in my new pc will there be an activation error. Thanks
Have you already updated your current PC from an older version of Windows to Windows 10?
If you have you are out of luck as it ties the key to your motherboard.
If you have not updated then follow Mean Machine's advice above and download Windows 10 and then use your current Windows 7 or 8 product key to install Windows 10.
Please keep in mind it seems Microsoft's "Free" Win 10 upgrade supposedly expires on July 29th so I would suggest doing this before then or it may not work.