In the case of a modern graphics card like a GeForce 8800 or a Radeon HD 2900, 3DMark 99 already runs as SM3.0/4.0 shaders as the chips have no facility to do fixed function processing. If we took the code for 99 and turned it all into DX10 code, it would look practically no different (less banding in places, but that's it). To take full advantage of what DX10 can offer, it would mean completely redoing the whole thing: new models, new textures, new lighting routines and so on. Given that we're already working on the next 3DMark which is DX10-only, there's no point in doing this. Besides, I think each 3DMark perfectly encapsulates just what is possible with each Direct3D revision at that time and going back to change things defeats that purpose.