Your xorg.conf looks like this: Section "ServerLayout"
	Identifier     "X.org Configured"
	Screen      0  "Screen0" 0 0
	InputDevice    "Mouse0" "CorePointer"
	InputDevice    "Keyboard0" "CoreKeyboard"
	InputDevice	"Alps Touchpad" "AlwaysCore"
EndSection
whereas mine looks like this: Section "ServerLayout"
	Identifier		"X.org Configured"
	Screen      0  "Screen0" 0 0
	InputDevice		"Alps Touchpad"  "CorePointer"
	InputDevice		"Keyboard0" "CoreKeyboard"
EndSection
How is the Dell XPS m140 set up - is it a touchpad alone, a touchpad/pointing stick combo, or?
This section in your xorg.xonf should turn off tapping: Section "InputDevice"
	Identifier	"Alps Touchpad"
	Driver  	"synaptics"
	Option 		"Device"  	"/dev/psaux"
	Option		"Protocol"	"auto-dev"
	Option		"SHMConfig"	"true"
	Option "MaxTapTime" "180"
	Option "FingerPress" "400"
	Option "TouchpadOff" "2"
EndSection..but from your xorg.0.log, your touchpad is not being recognised is it an alps touchpad, a synaptics touchpad or another brand?