It was both. I dont remember what earlier version we tried but i know that one was a 304.XX but less than 88. And one was 310.XX. The 319.XX (one that is currently latest for many gtx cards from nvidia, including older quadro 3700 that we also got on some computers here) didnt work at all so clearly not supported driver for the quadro fx 4000.
Im testing on a GTX 680 now and happy to say that houdinis viewport outperforms maya (and maya 2.0 viewport) and blender in pure opengl performance. We did fps comparison on 10+ million poly sculpts from zbrush when moving around the viewport in different modes like wireframe, smooth shaded and smooth shaded with wires.. Also it was faster in selection speeds on both faces, points and edges (lasso + paint selection as well).