Much to my amazement, the XF401 phase 1 installed nicely (after using the --force-depends) on a new potato machine. Unfortunately, I haven't managed to take advantage of the DRI because most of the Mesa demos (and plib1) rely on having GLU available.
Is there anything 'different' about the xlibgl1 contents that would preclude running happily, if I simply recompile mesa to just create GLU ? Not that I'm impatient ... I'd just rather not wait! It seems wrong to run software mesa on a GeForce... Grin.