I am running a Dell Latitude D620 with an nvidia Quadro NVS 110M. I previously used EnvyNG to get the nvidia driver, and I managed to get twinview working with the nvidia control tool (I can't really remember what it is called). BUT, my internet started getting really really slow on some pages, especially pages where information had to be entered into a form. That did not just apply to firefox, but to konqueror as well. So I used envyNG to uninstall the driver. Now my internet works, but twinview doesn't *exasperated sadness*.

<Ummm///I think I love you?>

EDIT: oh yeah, my external monitor is a DELL 1707 FPT, and my laptop lcd is made by seiko i think
EDIT#2: Kubuntu Hardy Heron

Here's my xorg.conf

# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings: version 1.0 (buildd@vernadsky) Thu Jun 5 09:26:53 UTC 2008

# xorg.conf (X.Org X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the xorg.conf manual page.
# (Type "man xorg.conf" at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
# sudo dpkg-reconfigure -phigh xserver-xorg

Section "ServerLayout"
Identifier "Default Layout"
screen 0 "Screen0" 0 0
Inputdevice "Synaptics Touchpad"
EndSection

Section "Module"
Load "glx"
EndSection

Section "ServerFlags"
Option "Xinerama" "0"
EndSection

Section "InputDevice"
Identifier "Generic Keyboard"
Driver "kbd"
Option "XkbRules" "xorg"
Option "XkbModel" "pc105"
Option "XkbLayout" "us"
EndSection

Section "InputDevice"
Identifier "Configured Mouse"
Driver "mouse"
Option "CorePointer"
EndSection

Section "InputDevice"
Identifier "Synaptics Touchpad"
Driver "synaptics"
Option "SendCoreEvents" "true"
Option "Device" "/dev/psaux"
Option "Protocol" "auto-dev"
Option "HorizEdgeScroll" "0"
EndSection

Section "Monitor"
Identifier "Configured Monitor"
EndSection

Section "Monitor"
Identifier "Monitor0"
Vendorname "Unknown"
Modelname "DELL 1707FP"
Horizsync 30.0 - 81.0
Vertrefresh 56.0 - 76.0
EndSection

Section "Monitor"
Identifier "Monitor1"
Vendorname "Unknown"
Modelname "DELL 1707FP"
Horizsync 30.0 - 81.0
Vertrefresh 56.0 - 76.0
EndSection

Section "Device"
Identifier "Configured Video Device"
Driver "nv"
Option "NoLogo" "True"
EndSection

Section "Device"
Identifier "Videocard0"
Driver "nv"
Vendorname "NVIDIA Corporation"
Boardname "Quadro NVS 110M"
EndSection

Section "Device"
Identifier "Videocard1"
Driver "nv"
Vendorname "NVIDIA Corporation"
Boardname "Quadro NVS 110M"
Busid "PCI:1:0:0"
Screen 1
EndSection

Section "Screen"
Identifier "Default Screen"
Device "Configured Video Device"
Monitor "Configured Monitor"
Defaultdepth 24
EndSection

Section "Screen"

# Removed Option "TwinView" "0"
# Removed Option "metamodes" "DFP: 1280x800 +0+0"
# Removed Option "metamodes" "CRT: nvidia-auto-select +1280+0, DFP: 1280x800 +0+0"
Identifier "Screen0"
Device "Videocard0"
Monitor "Monitor0"
Defaultdepth 24
Option "TwinView" "1"
Option "TwinViewXineramaInfoOrder" "CRT-0"
Option "metamodes" "CRT: nvidia-auto-select +0+0, DFP: 1280x800 +0+0"
EndSection

Section "Screen"
Identifier "Screen1"
Device "Videocard1"
Monitor "Monitor1"
Defaultdepth 24
Option "TwinView" "0"
Option "metamodes" "CRT: nvidia-auto-select +0+0"
EndSection

Section "Extensions"
EndSection

mellow,

as no-one has replied and I do not have your hardware I will offer some suggestions.

1) make a backup of your existing /etc/X11/xorg.conf and with luck you have an old xorg that did work?

post that old file please.

2) Notice your new file only names 2 Dells and that ain't right is it. It looks like you always leave the dell connected but that is not always going to be is it?

I am thinking you could copy and paste from the old file to the new file using root powers.
but you will need to know how to use a live cd to rescue and replace the xorg file if things go awry.

3) Name your live cd and what experience you have with it pls.

just from a quick look, it seems like your issue is because you defining 2 separate screens but only using one in ServerLayout.
here's my xorg.conf, also using an nvidia card but with the proprietary drivers. of course this is on a desktop so ymmv.

only the sections relevant to display:
you'll notice i only use one screen, one device, and one monitor because i have it set up for twinview spanning one large desktop which you may not want unless you will always have the second monitor hooked up.
for using the displays as 2 individual desktops you should be able to use your current conf and just add something to the effect of
to your ServerLayout section.

also, the nvidia configuration tool you forgot the name of is nvidia-settings