OK, so I have had success with a non-existent xorg.conf, as far as getting a basic 1400x1050 resolution going. I currently have a few reaons for having an xorg.conf:

• because I have an extra screen when I'm at work, and I want to use xrandr to expand my desktop across it
• I tweak the configuration for my touchpad
• I disable capslock and make the 'windows' key an extra meta

It could probably be shorter but anyway, here it is, in all it's glory:

Section "InputDevice"
        Identifier      "Generic Keyboard"
        Driver          "kbd"
        Option          "CoreKeyboard"
        Option          "XkbRules"      "xorg"
        Option          "XkbModel"      "pc104"
        Option          "XkbLayout"     "us"
        Option          "XkbOptions"    "ctrl:nocaps,altwin:meta_win"
EndSection

Section "InputDevice"
        Identifier      "Configured Mouse"
        Driver          "mouse"
        Option          "Emulate3Buttons"       "true"
        Option          "CorePointer"
        Option          "Device"                "/dev/input/mice"
        Option          "Protocol"              "ImPS/2"
EndSection

Section "InputDevice"
        Identifier      "Synaptics Touchpad"
        Driver          "synaptics"
        Option          "SendCoreEvents"        "true"
        Option          "Device"                "/dev/psaux"
        Option          "Protocol"              "auto-dev"
        Option          "SHMConfig"             "true"
        Option          "MinSpeed"              "0.04"
        Option          "MaxSpeed"              "0.75"
        Option          "AccelFactor"           "0.005"
        Option          "VertScrollDelta"       "20"
        Option          "HorizScrollDelta"      "50"
        Option          "HorizEdgeScroll"       "0"
        Option          "VertEdgeScroll"        "0"
        Option          "VertTwoFingerScroll"   "1"
        Option          "HorizTwoFingerScroll"  "1"
        Option          "ScrollButtonRepeat"    "0"
EndSection

Section "Device"
        Identifier      "Intel 945GM Graphics Controller"
        Driver          "intel"
        BusID           "PCI:0:2:0"
        Option          "UseFBDev"              "true"
        Option          "NoAccel"
EndSection

Section "Monitor"
        Identifier      "Configured Monitor"
        Option          "DPMS"
        DisplaySize     304 228
EndSection

Section "Screen"
        Identifier      "Default Screen"
        Monitor         "Configured Monitor"
        DefaultDepth    24
        SubSection "Display"
                Modes           "1400x1050"
                Virtual         2880 2048
        EndSubSection
EndSection

Section "ServerLayout"
        Identifier      "Default Layout"
        Screen          "Default Screen"
        InputDevice     "Generic Keyboard"
        InputDevice     "Configured Mouse"
        InputDevice     "Synaptics Touchpad"
EndSection

This is currently working with xserver-xorg-video-intel 1.4.1~git20080131-1 on xorg 1.4.0 (i.e. current Debian Sid).

Hope that's useful,
Andrew McMillan.