Option "DDC" "0"
Option "VBERestore" "0"
Without them, the setup breaks unless you wait for X to start before plugging in the external monitor.
Section "Device" Identifier "Videocard0" Driver "i810" VendorName "Videocard vendor" BoardName "Intel Corporation 82852/855GM Integrated Graphics Device" BusID "PCI:0:2:0" Screen 0 Option "MonitorLayout" "CRT,LFP" Option "AGPMode" "0" VideoRam 32768 Option "DDC" "0" Option "VBERestore" "0" EndSection Section "Device" Identifier "Videocard1" Driver "i810" VendorName "Videocard vendor" BoardName "Intel Corporation 82852/855GM Integrated Graphics Device" BusID "PCI:0:2:0" Screen 1 Option "MonitorLayout" "CRT,LFP" Option "AGPMode" "0" VideoRam 32768 Option "DDC" "0" Option "VBERestore" "0" EndSection Section "Monitor" Identifier "Laptop LCD" Option "DPMS" HorizSync 30-81 VertRefresh 56-75 EndSection Section "Monitor" Identifier "Desktop CRT" Option "DPMS" HorizSync 30-81 VertRefresh 56-75 EndSection Section "Screen" Identifier "Screen0" Device "Videocard0" Monitor "Laptop LCD" DefaultDepth 24 SubSection "Display" Depth 24 Modes "1024x768" EndSubSection EndSection Section "Screen" Identifier "Screen1" Device "Videocard1" Monitor "Desktop CRT" DefaultDepth 24 SubSection "Display" Depth 24 Modes "1280x1024" EndSubSection EndSection Section "ServerLayout" Identifier "DefaultLayout" Screen 0 "Screen0" 0 0 Screen 1 "Screen1" LeftOf "Screen0" InputDevice "Generic Keyboard" InputDevice "Configured Mouse" InputDevice "Synaptics Touchpad" Option "Xinerama" Option "Clone" "Off" EndSection Section "DRI" Mode 0666 EndSection