I had a power supply failure. I figured while I was replacing that a new video card would be nice. Having more money than brains I decided "What the heck, might as well replace the CPU/motherboard and memory".
I figured I would have to reinstall Windows and lose the data on my boot disk. I have always had to do that in the past.
I turned it on for the first time and everything worked fine after a number of updates Windows prompted me to install it. So much easier than the old days when you were forced to reinstall. All I had to do was reactivate Windows using my Windows account.