The PC right now has Windows and it's a pain to use of course. I wanted to install LE but I've seen that support has been dropped
If I install the older versions, would it matter for my father who occasionally just wants to stream 80s musical videos?
Support for i386 was dropped approx. 2-years before LE existed (in OpenELEC days) and the last release was OE 5.0. If you can still find the installer image AND only wanted to play local media it might work, but I'd expect challenges with add-ons AND there will be zero support from anyone sane for releases that old. Good luck 
if I remember correctly thew N270 can just handle SD H264 or DVD everything else won't work. Depending from "where" your stream it there might be problems if you use a very old OS version.
You can run Windows 10 at it, it is horrible slow but still comparable to the XP Performance - if you have at least 2GB RAM
Otherwise get some 50€ refurbished pc from ebay, its much faster.
