was easy with the possibility to upgrade from previous windows to win 10, but now no more because the free win 10 upgrade ended, so i have my torrent copy of win 7 or win 10 for that, just use a bootable usb, you can make it bootable with rufus
if you mean ubuntu i'm not too familiar with it, i prefer to use linx on a VM
Windows 10 upgrade not free anymore?
Well... it's still free, sort of, depends on... things
https://www.microsoft.com/en-us/accessibility/windows10upgrade?tduid=(3d0a9b914f4e1448707e8ed162c69bb7)(266696)(1503186)(skim33330X911647Xa68e5caea18d748c47809d1b2ce9d04b)()