For those struggling with getting Dual Display supported on their nVidea Quadro NVS 140M graphics card based DELL notebook, please note that I (finally) got it working by removing any VGA kext injector (like Natit.kext or NVinjectorGo.kext) en just activating the GraphicsEnabler key for Chameleon 2.0-RC4 (please note that you DO NEED Chameleon 2.0-RC4 as earlier releases do not seem to work!) in the com.apple.Boot.plist by adding:

<key>GraphicsEnabler</key>
<string>Yes</string>

I now have 1920x1080x32 on my external DELL 2407WFP (recognized as such) and 1680x1050x32 on the internal display. Both mirrored as extended desktop work flawlessly. The only downside I still have is that only the VGA output port works (HDMI port does not) but that's really a minor issue.

These are the kexts I've currently installed on my Snow Leopard 10.6.3:
AppleACPIBatteryManager.kext
AppleACPIPS2Nub.kext
AppleBCM5751Ethernet.kext
ApplePS2Controller.kext
fakesmc.kext
NullCPUPowerManagement.kext
OSXRestart.kext
SleepEnabler.kext (10.6.3 version)
VoodooHDA.kext (removed AppleHDA.kext)

which enabled:
- Battery management (Battery status in menu bar is fully operational)
- USB (mouse, external keyboard, headset,...)
- Built in Ethernet
- Trackpad
- Sleep mode
- Sound (both Output AND Input for built in speakers/mic AND external Logitech USB Headset/A-0374A, even the volume up/down and mute buttons are fully operational!)

Next things to address: Shut Down/Restart and WiFi...