The Register provides a surprising report that the NVIDIA GeForce 2 DXTC (texture compression) is broken. The fault seems to lie in the hardware and does not appear to be correctable with better drivers. There are two screenshots of the sky under the Dagoth Moor Zoological Gardens demo taken with a Radeon and GF2 MX. This follows a tetralogy of articles at Game Basement which can be found here, here, here, and here as well as other places which have led to similar conclusions. Thanks to gill as well.
Update: Sci-Fi Gaming is reporting that the NVIDIA screenshot is correct. It is the Radeon which lacks the support of hardware fog & haze effects according to WXP's DMZG programmer Patrick Moynihan.