I use my iPad Mini Retina.

I read on my phone, and watch videos on my kindle.

I love my paperwhite as well - both for my own ebooks and those I borrow via Overdrive. In particular, I love increasing the font and reading without my glasses when I'm in bed. I also love the battery life - at least a week given the way I read (generally a couple of hours a day).

I bought the kindle DX last time around because it was the only one that was still offering a keyboard. It took a bit to get used to the bigger size, but I like it now. I use an iPad for graphic novels and cookbooks.

I use Aldiko on my Samsung Galaxy tablet, I love Aldiko, I can set up tags and collections to sort everything by. There is a glare factor, though, and I wish I could bring myself to get a Paperwhite just for fic, but my tablet does everything.

My Mom's old computer has become intolerably slow. All she does is browsing, manager her banks account, email, and the very occasional speech for which she uses Open Office. 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.) So what specs? I mean I see some really inexpensive windows 10 computers but I worry that slow processors, slow buses and slow hard drives will slow her down. OTOH, she does not need anything super. The hard drive needs to basically hold the OS, anti-malware, firefox, thunderbird and open office. Here "data" that is actual work will never come close to half a gig. So the low end sized disks (500 Gig) or whatever will work fine as long as they are not slow. Because of constant software updates, and constant anti-malware scans they do have to be reasonably fast. So that stuff that is supposed to go on in the background can go on into the backround and still leave her enough bandwidth to actually do things. So how do I distinguish a bargain from something that really won't support the basic functions she needs. I'd kind of like a little "cushion" so it will contiue to work once windows stops lowering footprint, and updates with a bunch of bloatware, as it probably will eventually.

Typo, I think pretty much anything modern you get will be able to handle that your mom's needs. Are you looking for a laptop or a desktop?

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. This can mostly be fixed (there are already articles on the net about how to do it).

They've also set it up so that they will (not just can) push updates down onto the system without your permission. This cannot be overridden. I don't think that should be much of a big deal to someone like your mother who is only using the most basic functions, but it a problem for folks doing stuff that might get bricked by a patch.

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.)