Thanks for wattOS-R9-LXDE(32bit) to revive my 12-years-old IBM ThinkPad X40.
It has 1.5GB memory and 40GB HDD which was not adequate for most of Ubuntu flavor distro except Lubuntu.
Since I was using X40 as a remote thin client, I did not need most of Lubuntu application.
After installing wattOS-R9-LXDE, X40 works perfectly as I expected.
Thanks for great job!