I just stared playing around with this Linux distribution.
It's about as solid as your going to get. They are using XFCE and OpenBox for the UI, and it is extremely responsive, almost lightening fast on older hardware.
This is a really fascinating study in the ability of Linux and the gradual migration towards the open source platform in general.
I will be getting back with ya on this one, and the new KXStudio Linux is out and about, supposedly they are migrating to a pure ~or~ unsure total Debian or a mixture of Ubuntu. Either way it sounds good to me, for one reason or another I enjoy using Linux, it definitely keeps me on my toe's, so to speak :_)