When I wrote on Monday about the ins and outs of what counts as, I was worried that it might turn into a flame war. But, instead, readers sent in a whole bunch of really good questions on the intricacies of licensing Windows 7 that went beyond the basics I had covered.
Things like dual-boot machines and systems with beta versions of the operating system raise all sorts of interesting licensing challenges.
Before we dive into the edge cases, though, here's a recap of the basics on Windows 7.
For those upgrading their PC, they can choose from Home Premium, Professional or Ultimate editions. There is also a family pack that includes three upgrade licenses for Windows 7 Home Premium.
Many people will have to do what is known as a custom or "clean" installation, which involves backing up one's data, installing Windows 7, then restoring the data and re-installing all applications.
All users of XP will have to go this route, as will those moving from a 32-bit version of Vista to a 64-bit version of Windows 7 (or vice versa), as well as those who are moving from a higher-end version of Windows Vista to a lower-end version of Windows 7.
Those moving from Windows Vista to the same version of Windows 7 (or to Ultimate) can do what is known as an "in-place" upgrade, which preserves files and applications.
Anyway, on to the tough cases. Here are some of the questions that readers sent me, as well as the answers I heard back from Microsoft.
Q: I installed the release candidate version of Windows 7 on a reformatted hard drive that previously had Windows Vista installed. Can I use the Windows 7 Home Premium Upgrade version to install a licensed copy?
A: Yes. You can do a custom installation ("clean install") to Windows 7 using the upgrade. The Windows 7 installer will detect you have the RC installed, enabling you to do this.
Q: Try as I might, I haven't been able to find any reliable information on whether I can upgrade from Vista Home Premium Edition (that came with my HP Laptop) straight to Windows 7 Professional/Ultimate, or whether it is only possible to upgrade from "Vista Home Premium" to "Windows 7 Home Premium."
A: You can do an in-place upgrade from Home Premium to Ultimate, provided you aren't switching from 32-bit to 64-bit or vice versa. Going from Home Premium to professional, however, requires a custom installation. (For a chart of which versions can be done via in-place upgrades, check out this Microsoft Web page.)
Q: I have Vista Basic on two computers and XP on the other one. So all I would have to do is use a Windows 7 upgrade disc on all three computers? Does one disc do one computer or will it do all three? I live in Canada, not the U.S.
A: In both the U.S. and Canada, your best bet is probably the Windows 7 family pack, which offers a license to upgrade up to three PCs.
Q: Can you use an upgrade disk to run XP (or Vista) in dual-boot (meaning that one partition or hard drive has the older operating system and the other partition or drive has Windows 7?
A: Microsoft treats a dual-boot machine as if it were two PCs, so you can only use the upgrade if you are installing over an existing Windows partition. So, unless you have two licenses already on that system, you will need a full copy of Windows 7.
Q: What about upgrading a Mac?
A: In order to qualify to use the upgrade version, Mac owners need to be running a previously licensed full copy of Windows (not just a beta version). That applies whether one they are using Windows in Boot Camp or using a virtualization product like Parallels or VMWare's Fusion.