Old Laptops never die!
I use those as you said, not as a server, daily use under LINUX of course.
Much better than any WIN oder MAC-OS.
(Their updates upgrades which don't work and are causing really troubles)
Sometimes a little bit tricky, but everybody who knows how computers really work can handle it.
And don't forget, whenever there is a problem the LINUX-community is as helpful as we here are.