Here's an interesting experience I had on my third machine upgrading to Windows 10 from Windows 7. I nearly gave up, but it's all upgraded now! Maybe you have a similar problem?
This was a pretty old machine, and it had been running Windows 7 for many years -- 64-bit, with an AMD CPU and a 6150 Nvidia graphics chip on board. All had been well, even though it had 2GB RAM and a pretty small hard drive. My wife had been using it for email, calendar, and Word and Publisher projects. I got her a newer machine, already upgraded to Windows 10 Home.
But I still wanted to upgrade this "old" Windows 7 machine for me. I got the little Win 10 icon in the lower right (we used to call it the tray) of the taskbar that eventually said, as I remember, "We are sorry, but we are unable to update this machine, for two reasons: The CPU is NOT supported, and the 6150 has no driver. When I tried to install anyway I received this message: "You canít install Windows 8.1 because your processor doesnít support CompareExchange128." Apparently this problem arose when Windows 8 came out, and in researching I found more details: "The limitation on 64 bit Windows 8.1 applies to AMD Athlon 64 / Opteron 1, 2 or 8 series CPU on Socket 939 754 etc." So it looked like I was out of luck -- stay with Windows 7 or get a "new" old machine. But I did discover that this problem only applied to machines running the 64-bit version! So I could maybe upgrade ONLY a 32-bit version, but would have to eventually reinstall all applications to run under Windows 10.
So, here's what I did:
1) Ran ProduKey (mentioned at the July meeting) and wrote down the product key for the 64-bit Windows 7 version that was un-upgrade-able. (I had originally bought the Windows 7 "Family Upgrade Pack" and it came with three packages, each with 2 DVDs -- one each for 32-bit and 64-bit versions, each package with its own product key.)
2) Installed a different small hard drive (could have formatted the current one, but didn't), then booted the DVD for the 32-bit version of Windows 7, formatted this "new" hard drive and installed Win7-32 on it. You can do this as well by booting the DVD, installing it as a clean install first and skipping any request for a product key. Then you boot the "new" Windows 7 hard drive, and with the DVD still in the drive you open Windows Explorer, go over to Drive D:, and click Setup.exe to install Windows 7 again -- this time as an upgrade. When it asks you for the product key give it the one written down for the 64-bit version (it's only an upgrade key) and it should activate just fine.
4) Then I went to Paul Thurrott's page (http://www.microsoft.com/en-us/software-download/windows10
) on how to download Windows 10 and upgrade right now. I was asked if I wanted to upgrade or clean install -- picked upgrade so it will read the Win 7 Key and know that I am legit.
It's done and works just fine. The bottom line is that you CAN upgrade Windows 7 32-bit to Windows 10 32-bit, even though you can't do the 64-bit versions on my particular computer. I can't address more than 4GB of memory (actually closer to 3GB) with this 32 bit version, AND the Device Manager shows it's using the Microsoft Basic Display Adapter instead of having a 6150 driver, but this will be a small household server and should run just fine.
Good Luck, your mileage may vary, all disclaimers apply, etc...