Yes Kari, you definitely can Not install 64bit Windows on 32bit architecture.

If you were wondering if that was my mistake, then No, all the machines Ive tested on were x64 (eg Core 2 Duo ......

I strangely got this dreaded error too while installing Windows 10 Pro (32bit and 64bit) final edition.

Turns out it was because of my USB Flash drive ! ! !

What i found was Win 10 Preview...