there's my noob findings, I hope it can help another noob !

/etc/X11/xorg.conf seems to be empty in the new 9.10 ...
But I wanted to have and headless computer run trought VNC.
but I format my old 9.04 harddrive !!!

So I guest I found the basic xconf file who can work with VNC,

Code:
Section "Device"
  Identifier "Configured Video Device"
EndSection

Section "Monitor"
  Identifier "Configured Monitor"
  HorizSync 31-101
  VertRefresh 60-160
EndSection

Section "Screen"
  Identifier "Default Screen"
  Monitor "Configured Monitor"
  Device "Configured Video Device"
SubSection "Display"
  Depth 24
  Modes "1280x1024" "800x600"
EndSubSection
EndSection

Add the resolution you want, and check to see if horizontal and vertical sync are ok with your monitor...

With that I boot my headless computer without any problem.

Please fell free to add more information, for people noob like us
)