Dell Optiplex GX100/GX110
i810 Chip set.
Xconfigurator 4.3.38-1, 4.3.35-1, and 4.3.40-1.

If 1MB VRAM is selected, 640x480 24bpp works, but nothing in 16bpp works
in any case.  Xconfigurator may crash on exit, leaving a
black screen and a mouse.  If it does not crash, the mouse will still
remain in the terminal and usually cause erratic highlighting and
return characters when moved (without pressing any buttons).
The mouse is set to generic PS/2 whereas there was a MS Intellimouse
attached.  Setting it to Intellimouse does not fix this problem.

At 1MB, choosing 16bpp causes "there is something wrong with the
X configuration" error.  If 16bpp ever works in Xconfigurator,
it causes a crash of X with the drm library claimed to be at version
1.1.0 and expected 1.0.x.
This was with a Dell D1025TM Trinitron monitor.

4MB is the proper VRAM setting but Xconfigurator defaulted to 1.  At 4MB I 
tested the config.  
Picking a single or multiple modes in 8 or 24bpp worked fine.  If at least 
5 modes were
selected 16bpp worked and all modes were workable (switched with ctrl-alt-
arrow).  If any less
were selected, Xconfigurator would say that there was something wrong with 
the Xconfiguration.
In addition, the size of the virtual desktop was 1280x1024 under these 
modes.  Picking other modes, 
the desktop was the size of the screen.