She needs to be on a windows computer (unless there is an easy way to share printers between windows and linux - something that looks a bit tricky to me.)

I don't know about the printer-sharing issue, so this might be a no-go, but Tim got his dad a Chromebox because his dad has pretty much exactly the same computer needs as your mom. His dad's Windows machine was full of viruses, which is not a problem with a Chromebox. They're also pretty dang inexpensive, especially if you don't need to upgrade her monitor or keyboard. And his dad, who is 0% computer-savvy, had not problem making the switch from the Windows OS to the Chromebox.

(Tim also bought himself a Chromebox so that he could remotely troubleshoot his dad's computer, which was a stroke of brilliance.)

Yeah, planning to do privacy adjustments, and also make interface as much like Windows 7 as possible. So, for example, is 4 Gig of Ram and a processor that is many generations old OK?(Teppy - in terms of the chromebook - problem is, her computer needs to be the print server for other computers. Chrome uses cloud print - It can print on a printer that is on a windows printer, but can't host a printer.)

From what I've heard, Win 10 can run pretty well on older equipment, so I think you'll be okay. I might go for more RAM if it's not a deal breaker.

and also make interface as much like Windows 7 as possible

Yeah, I just did this to my mom's Win 8 laptop. (Not that I blame her. I hates it, precious.)

(Teppy - in terms of the chromebook - problem is, her computer needs to be the print server for other computers. Chrome uses cloud print - It can print on a printer that is on a windows printer, but can't host a printer.)

Ah. Makes perfect sense. For Tim's dad, we had to get him a wireless router and a printer that can print via wifi, but now all the grandkids are happy because the house has a wifi network.

I've been fighting Win 8 since I had to get a new PC is spring, and I loathe it so much I'm thinking of jumping to Win 10 rather than trying to beat Win 8 into submission. Aside from the privacy thing, which I knew about, anything else I should watch for?

There's a good overview of both the good and the bad here.

Also:

Microsoft can disable your pirated games and illegal hardware which is about what you agree to now when you agree to the EULA for Microsoft's Live Services, which includes Cortana, their answer to Siri. What they seem to have done is just copied the EULA from XBox verbatim, and most are assuming that the games and illegal hardware are the kind of stuff XBox hackers are fond of, rather than using a non-certified video card, but who knows.

That Forbes article you link suggests waiting until Ocober to upgrade existing Windows computer - gives them time to get bugs out. If I get her a brand new windows computer I'll probably do the free upgrade as soon as it will let me.

...Win 10...anything else I should watch for?

Managing LANs and wireless connections has become over-simplified, there is little in the way of options, diagnostics, or tools. If you can connect, great, but if you cannot then there is not much you can do about it.

IMHO the amusement provided by Cortana is not worth the resource usage and battery drain.

My 8-year-old 17" laptop has 2GB RAM and a 1.50GHz processor. It came with Vista, and it upgraded to Win7 okay, but Win10 is a bit much for it. I saw noticeable slowdowns with the new Microsoft Edge browser, Windows Explorer, and OpenOffice. I reverted it to Win7 and intend to keep it that way.

This is good info. When I got my new laptop last fall, I special ordered one with Windows 7 because I knew I didn't want 8. Have reserved Windows 10 but haven't upgraded yet. All instincts tell me not to. I don't even use Cortana on my phone.

Also if you're not yet aware of it, although Windows 10 is apparently a great OS, by default all privacy settings are turned off, allowing Microsoft to collect all sorts of data about your mom.

I discovered during the install that is will ask you at some point if you want to use express settings or customize settings. I choose customize and it let me turn on the privacy settings there so I didn't have to hunt them down latter. Windows 10 works just fine on my desktop but it's an i5 with 16GB of RAM (-4GB for the Linux server that runs in a VM) and a SSD so it damn well better run fine.

While it runs just fine, I don't really find anything compelling about it that would make me want to upgrade from 7 or 8. I kinda prefer the Windows 7 start menu too.

If you want to make Windows 8 act like 7, I'd really suggest the Start8 program from Stardock. It has a free trial and is only $5 if you like it. It's a must get for me on any Windows 8 computer.