Q4OS - Debian based with Trinity Desktop Environment.
Q4OS is a fast and powerful operating system based on the latest technologies while offering a highly productive desktop environment.
Their focus is on security, reliability, long-term stability and conservative integration of verified new features.
System is distinguished by speed and very low hardware requirements, runs great on brand new machines as well as legacy computers. It is also very applicable for virtualization and cloud computing..
If you have any problems downloading or installing you can find help in the friendly community forum.
I also have a full install guide covering everything you should need to know to get you up and running in no time at all.