Nobody knows the answer to your question and will not know until at least 29th July when Window 10 is released. At that stage, an upgrade advisor to run on Vista & XP may be made available or it may be some time later for all anybody knows.
However, the system requirements for Windows 10 are virtually the same as for Windows 8.1 so you can run the Windows 8 upgrade advisor on Vista & XP computers.
Do note that any result that says "may be a problem" for any particular device or application means that Microsoft do not know if anybody makes compatible drivers for the device / compatible updates for the software so you would have to contact the maker
to find out.
The Windows 8 upgrade advisor cannot even run on Win98 or WinMe so I think that tells you the answer for those systems.
Try*3 - a user Dell Inspirons 7779, 1545, 9300; Windows 10 Home x64 & Pro x86; Office Pro 2007; HP DJ2540; HTC UPlay [Android 6.0], MyPhoneExplorer
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