I can confirm that the colours are now correct and the gfx are good on my X5000 with X1950 card installed.
SuperTuxKart displays similar broken graphics with the X1900 & X1950 cards.
(Note the graphics are fine in both games with supported RadeopnHD gfx cards and most supported RadeonHD also produce better benchmarks than the X19xx cards.)
Trevor
PS I would have attached an image but it says the boards attachment quota has been exceeded?