if I understood correctly, the best texture, in DDS format, can only be used with NVidia proprietary drivers, right?
Compressed dds likely doesn't work on free drivers, yes. But Chris has the same texture also in png format - that will cause more memory occupancy and a longer loading time (I'm guessing some 2 minutes), but once it's loaded, you should see the same visuals with the same performance as if you would use dds. I have not tried how much worse the memory load with png is though.