I have two Asus X551 laptops that are about 8 years old. One my wife
uses as her primary computing device, and one I keep for when I have
to travel (which admittedly has not been much the past few
years). They both have failed batteries and probably soon-to-die
hard drives, but the displays are still fine.

Unlike more recent laptops, they can be disassembled, so rather than
buy replacements, I opted for a hardware refresh. $140CAD bought two
1TB SSDs and a new battery for each. I've already installed them in
one, along with a fresh Fedora (LXDE spin) install. That one is
noticeably faster with the SSD, and my wife appreciates the newer
version of Firefox. It had been running an old Debian 8 install, and
was increasingly failing to load "modern" websites properly. And
while I don't care for Fedora myself, it was easy to install and
simple for her to use as a non-technical person. I installed one
release back from the current one (so v36), I'll update it to v37
when v38 comes out. I figure that is the easiest way to get some
stability with Fedora.

I'll probably refresh mine this weekend, although I have not yet
decided which OS to install. It has Slackware 14.2 on it now, but
we'll see. In any case, it's nice to work with older tech that
allows one to take it apart and replace or upgrade components. I
hope to get at least another five years out of these laptops.