Make Sure You Understand Before the Deadline
Be sure you understand what upgrading to Windows 10 will, and will not, mean.
I'm fairly sure that any of our readers who want Windows 10 have already gone through the process to get it, and the rest have made it their mission to block it at all costs (or they don't use Windows).
Regardless, there has been quite a bit of misunderstanding over the last couple of years, so it's better to explain it now than a week from now. Upgrading to Windows 10 will not destroy your original Windows 7 or Windows 8.x license. What you are doing is using that license to register your machine with Windows 10, which Microsoft will create a digital entitlement for. That digital entitlement will be good “for the supported lifetime of the Windows 10-enabled device”.
There's three misconceptions that kept recurring from the above paragraph.
First, “the supported lifetime of the Windows 10-enabled device” doesn't mean that Microsoft will deactivate Windows 10 on you. Instead, it apparently means that Microsoft will continue to update Windows 10, and require that users will keep the OS somewhat up to date (especially the Home edition). If an old or weird piece of hardware or software in your device becomes incompatible with that update, even if it is critical for the device to function, then Microsoft is allowing itself to shrug and say “that sucks”. There's plenty of room for legitimate complaints about this, and Microsoft's recent pattern of weakened QA and support, but the specific complaint that Microsoft is just trying to charge you down the line? False.
Second, even though I already stated it earlier in this post, I want to be clear: you can still go back to Windows 7 or Windows 8.x. Microsoft is granting the Windows 10 license for the Windows 7 or Windows 8.x device in addition to the original Windows 7 or Windows 8.x license granted to it. The upgrade process even leaves the old OS on your drive for a month, allowing the user to roll back through a recovery process. I've heard people say that, occasionally, this process can screw a few things up. It's a good idea to manage your own backup before upgrading, and/or plan on re-installing Windows 7 or 8.x the old fashioned way.
This brings us to the third misconception: you can re-install Windows 10 later!
If you upgrade to Windows 10, decide that you're better with Windows 7 or 8.x for a while, but decide to upgrade again in a few years, then your machine (assuming the hardware didn't change enough to look like a new device) will still use that Windows 10 entitlement that was granted to you on your first, free upgrade. You will need to download the current Windows 10 image from Microsoft's website, but, when you install it, you should be able to just input an empty license key (if they still ask for it by that point) and Windows 10 will pull down validation from your old activation.
If you have decided to avoid Windows 10, but based that decision on the above three, incorrect points? You now have the tools to make an informed decision before time runs out. Upgrading to Windows 10 (Update (immediate): waiting until it verifies that it successfully activated!) and rolling back is annoying, and it could be a hassle if it doesn't go cleanly (or your go super-safe and back-up ahead of time), but it might save you some money in the future.
On the other hand, if you don't want Windows 10, and never want Windows 10, then Microsoft will apparently stop asking Windows 7 and Windows 8.x users starting on the 29th, give or take.