OmegaLinux
OmegaLinux is an Arch-based, rolling-release Linux distribution featuring the lightweight LXDE desktop. It is suitable for installation on older computers with as little as 1 GB of memory.
VS
MiniOS
MiniOS is a Debian-based Linux distribution which strives to be lightweight, modular, versatile and customisable. It comes in three editions, "Standard", "Toolbox" and "Ultra".