But just so that you know...the activation process keys on the hardware (motherboard, video card/chip, sound card/chip, NIC, hard drives, and memory installed). When those items appear to be changed, you likely will have to go to telephonic activation (which will only take 1/2 minutes) and where you will be requested to explain the changes.
If your old system was an OEM system and your license is (therefore) directly tied to that system alone, activation may be delayed.
I've changed motherboards, CPUs, hard drives, video card, NIC, and memory before...but never all at one time. My re-activations have always proceeded smoothly.