3dmark2000 broke recently because we aren't offering D16 anymore if a card doesn't expose it using GLX. On a Geforce 8800 it isn't offered by GLX (because the hardware is 24bit) but D3D9 on Windows offers it, so offer it too. Second D3D <= 7 requires it too as at that time there was no 24bit z-buffer.
The bug in 3Dmark2000 is a bug in ddraw, we do not report 24/32 bit formats in a way the game likes. I have a patch for that deep down in my sending queue that fixes the depth and stencil masks.
This patch is still perfectly valid, just pointing out that in case of 3DMark2k it fixes the wrong bug. Other older apps are likely do demand D16, just 3Dmark2000 doesn't.