If I buy Windows 8 and put it on a computer, can I then get the free upgrade to Windows 10? I'm not so sure this would work as then everyone would then just buy windows 8 instead of windows 10, which is more expensive.
If you are planning to buy Windows 8 you can upgrade to Windows 10 for free till 29th July 2016. After that Windows 10 will be paid.
If you have a legal copy of Win 7 OR Win 8.1, you can install the free upgrade to Win 10.
The version of Win 10 you see for sale is the full retail version, not an upgrade. The upgrade is free, but the full version is not. The full version does not require an existing OS to be present (because the full version doesn't upgrade anything). You can install the full retail version if you'd rather buy it and forego the upgrade process of Win 8.1 to Win 10, but it's totally up to you. If it's cheaper to buy Win 8.1 (or Win 7) and upgrade then I would go that route. But you need to make the decision fairly soon because the free offer expires 29 Jul 16
Trust me! Do not upgrade a computer. So many people have experienced trouble when upgrading. You're better off buying a W10. My mom experienced problems and hundreds of people came here to YA in regards to problems they encountered. Just buy a W10 computer.
You'd have to upgrade from 8 to 8.1 first (also for free), but yes. And you'd need to do it by July 29 which is when the Win10 upgrade offer expires.