One week back I have installed a fresh copy of OpenSUSE 11.3 on my personal laptop (Copmaq Presario CQ61),This is very stable and optimized for performance without using much CPU resource, and what I feel this is a lightweight distribution.
I have used KDE 4.5 which is the better than any other propitiatory Operating System in performance and User Interface.I can say that this is for layman users or normal users of computers. With my experience in using various Linux distributions,OpenSUSE resists to all update events and don't crash. This is the part that what I suggest this for a final user, for his daily activities.
OpenSUSE 11.3 uses KDE 4.5 along with Compiz Fusion for Desktop Cube kind of animations, which create an illusionary effects in UI for a normal user.
Compiz Fusion seeks to provide an easy and fun-to-use windowing environment, allowing use of the graphics hardware to provide impressive effects, amazing speed and unrivaled usefulness, Compiz Fusion is an open-source software project, meaning anyone can use it and contribute to it freely.
All in all, I've found that openSUSE is, once more, a great Linux distribution.