Windows 7 is not obsolete, it's fully supported and will remain under support for some time to come.
Again, why are you giving anyone tech advice? Windows 7 is not "fully supported". Microsoft hasn't released any new software for Windows 7 since 2014, other than security updates. No modern Windows software (UWP) runs on Windows 7. And, third party developers will stop legacy Windows 7 support relatively quickly.
The reason for recommending 7 over 10 is purely based on the age of his machine, in my experience (yes, experience) 10 has more compatibility issues with older machines than does 7, and finally the GUI of 7 will be much more familiar for a Vista user than that of 10.
You've been informed by two people that Windows 10 compatibility can be checked by a software tool. Sorry, I'm not going to put any weight on your experience, especially when it's not necessary. And, Windows 10 works just about as much like Vista as Windows 7 does. See Icon. Click Icon.
Because I am a tech lol.
You can download the disk, but only in trial mode unless a key is purchased.
Really, has to be purchased? Maybe that's why I questioned your advice about buying
a new operating system for an old computer and suggested going with Linux instead (which, just to let you know, is free).
Really? It's the processor architecture that determines whether an X86 or X64 OS should or can be used, in X86 trim Windows will only see 3.5GB of RAM but that has nothing at all to do with whether a 32 or 64 bit OS should be used.
You need to find another job and you need to stop giving people computer advice. Processor architecture has nothing to do with with choosing x86 or x64, as any Vista computer has a 64-bit processor. 32-bit Windows works better on computers with less than 4GB RAM (because 32-bit Windows has significantly lower memory requirements) and 32-bit Windows is compatibility with practically all windows Software. 64-bit Windows is not compatible with lots of older Windows software (anything with 16-bit code, which includes a lot of XP era software). So, you see, techie, the amount of RAM is the only relevant question.
$30-$40 is much cheaper than purchasing a new PC, a fresh install of a proven OS will breathe some new life into the machine.
Wrong. Any new copy of any version of Windows is over $100 (upgrade, OEM). And, $200 for retail, full-version. And, I wouldn't even sink $30 into an old Vista machine, not when you can get a new Windows 10 computers so cheap.
Mint, or any *nix OS still isn't the best choice for novice.
*nix? What's that asterisk stand for other than "Li". You thin Unix is even a remote consideration? Anyone who can manage an OS upgrade can manage Mint. Find another line of work.