Ed Bott has done two FAQs - so far - regarding upgrading to Windows 8. He has another coming soon.
The ultimate Windows 8 upgrade FAQ - Part 1 - ZDNet - You've got questions about the Windows 8 upgrade. Can you burn the upgrade files to DVD or a USB flash drive? Is it possible to go from a 32-bit Windows PC to 64-bit? Who qualifies for cheap upgrades? I've got the answers you're looking for.
Everything you need to know about Windows 8 upgrades (FAQ part 2) - ZDNet - Upgrading to Windows 8 is a straightforward process, but the details vary depending on your starting point. This second installment of my Windows 8 upgrade FAQ covers the ins and outs of different upgrade paths.
In the final installment: Everything you need to know about Windows 8 product keys and activation. (coming soon)
Thanks Ed Bott!