What touchpad device does your laptop use? Check your /etc/X11/xorg.conf file for input devices.
If it is a synaptics device, one of these options may need to be adjusted:
from the synaptics (4) manpage:
Option "FingerHigh" "integer"
When ﬁnger pressure goes above this value, the driver counts it as a touch. Property: "Synaptics
Option "FingerPress" "integer"
When ﬁnger pressure goes above this value, the driver counts it as a press. Currently a press is
equivalent to putting the touchpad in trackstick emulation mode. Property: "Synaptics Finger"
Option "MaxDoubleTapTime" "integer"
Maximum time (in milliseconds) for detecting a double tap. Property: "Synaptics Tap Durations"
Check your configuration option on Ubuntu. There may be a graphical program for making the adjustments, which would be easier than editing xorg.conf manually.