Made Windows 7 the default system with a 10-second counter if nothing is selected. Then transfered my Steam configuration from Windows 7 that kept same paths to my SSD where I install games, user configurations and credentials, no extra steps needed. Steam asked to allow to write some entries missing in the registry, which I allowed (because I knew they were written during the installation and since this was portable.).
Used my portable Steam from Windows 7.Bought a small SSD (256 GB) and a cheap Windows 10 (Pro, 64-bit) license, and installed Windows 10 in it, then after some clean up and setting it all up, used O&O ShutUp10++ to remove/disable all the extra crap.
My full experience with my favorite gaming computer where I still have Windows 7 (Home Premium, 64-bit): I did something like this half a year ago, and all it's working great.
