I had both (multi-boot) Windows 7 32bit and 7 64bit running on a Dell Dimension E520 with an Intel Q6600 CPU - in the Win7-64bit version it allowed an upgrade to Windows 10 and that works fine, but the Win10 Upgrade App showing on Win7-32 reports that the
Intel Q6600 "CPU isn't supported"!
The recent "fix" (KB2952664) for
the Appraiser CPU error has been installed but, when trying to force the Compatibility Appraiser to run it seems to fail, as the last test date is not incremented.
I will wait to see if the Appraiser runs sometime by itself and corrects this erroneous compatibility response, or I may try the BIOS to disabled "NX", as suggested, - that is if the E520 BIOS has that capability. (The reason I had to install a 64bit OS
was that one major programme is no longer supported in 32bit, but another program fails to work in 64bit mode!)