Much thanks for that solution of white textures problem.
First time I played Arx, it was on my old Voodoo Banshee and I had the same problem. The readme recognizes this only as a 3Dfx specific issue, suggesting the user should change value ForceMetalTwopass in CFG to "1". This doesn't work for my new 6600GT though... I'll try that solution from nVidia forums.