Upgrade your system with Windows 7 and a new PC.
Upgrade your system with Windows 7 and a new PC.
You can use your existing Windows 7 Ultimate installation without needing a new license. Just connect your hard drive and boot up normally.
A new licence is required. A single Windows licence applies only to one PC and often links to the motherboard. This allows upgrading CPU, RAM, HDD, etc., but not the motherboard itself. Swapping the motherboard counts as a different system.
Transferring the hard drive directly isn't typically recommended. It might cause issues with all the motherboard drivers, so you could need to install different drivers for the new motherboard, though this isn't always successful. Another concern is that your license key is likely an OEM product and may be branded. You can attempt to deactivate it on the existing system and reactivate it on the new one. Alternatively, you might try activating it via your phone, but if that fails, you're in a tough spot as mentioned earlier.