Someone said in another forum that I should post my experiences with ubuntu during installation. So here it is according to my installation on a Dell C610 Latitude laptop:
The following acpi-support configuration will successfully suspend the 2.6.22 and 2.6.23 kernel even while docked (in doubt, try alsa-1.0.15 instead of backported driver). You might want to mess with unloading additional modules if it doesn't work for you