If you can provide a Model number for your PC, we could help look into compatibility. For the most part even in the worst case scenario, you can typically use Vista Drivers for hardware devices if necessary, there are some cases where a Vista computer might not work properly with Windows 10.
*censored* to the issues regarding key reseller websites or ads that offer to sell you keys, you can find a lot of websites that claim to offer Windows 10 Keys for much cheaper than Microsoft sells them. You can also find a LOT of people who recommend the websites, and swear they are legitimate.
They aren't.
The reseller websites that do this are able to offer them for so cheap because they aren't legitimate. I've seen a few youtube channels who I otherwise expected to be reasonably competent stand by their claims that key resellers are legitimate, usually with some stupid anecdote "I bought a key a year ago and it still works" as if that proves it's legitimate. Don't believe them, because they have no idea what they are talking about.
I don't know all the ways reseller sites obtain them, but it seems like one approach is to directly ask MSDN subscribers to generate keys, offering 5-10 dollars for each key. I know this because I have received (and ignored) these requests from a few Key resellers over the last few years.
The reason that makes it not legitimate is that it violates the MSDN subscription terms. When such a violation is found, not only is the MSDN subscription terminated altogether but all generated product keys attached to that account are blacklisted.