1. This problem has existed in many previous incarnations of Xconfigurator 2. Some video cards, such as the Diamond Speedstar A50 and Diamond Viper(?) do not work with 32 bpp; they only work with 24 bpp. In such cases, Xconfigurator always writes 32 into XF86Config. 3. I can always fix this by editing XF86Config and changing the 32 to 24, but imagine how many new users are repulsed by the installation failing at this point! 4. The fix is probably quite trivial (but I use Perl rather than Python)
Xconfigurator now writes mode lines for 24 and 32 bits.