Libreelec on old hardware

the wiki says: NO

see:

https://wiki.libreelec.tv/hardware/intel-x86-64-generic

but I would try it anyway...

GPU support ???

alternative I would try ClearLinux to get a current and supported OS on the box for lower task usage (web, office):

Recommended minimum system requirements — Documentation for Clear Linux* project

cit.:"

Clear Linux* OS can run on most modern hardware and is capable of running with modest hardware resources. Out of the box, Clear Linux OS can run on a single CPU core, 1 GB RAM, and minimum of disk space of: ..."

- I can't figure if they mean desktop, too -

you could run the the "compatibility check tool" before (if you're running linux)

EDIT

installed a box:

as usual: fast(est) distro, cause optimized for Intel (well, running a Skylake CPU)

RAM usage: 1.1 GB, idle Gnome desktop

The issue is not whether you can install LE on it (maybe) but whether it runs any good once it's installed. Old laptops are generally slower, noisier, with worse media support, and use more power than an older Raspberry Pi2/3 board. Experimenting is $free though