Right click on my computer, click device manager, click mouse other pointing devices, right click touch pad disable it, to turn it back on right click and click enable
Most laptops have a button near the touchpad specifically for disabling the touchpad. In XP/Vista go to the Control Panel->Device Manager and disable the mouse there.
If available, click button next to touchpad. Otherwise, use Start, Control Panel, Mouse Icon. On Mouse Properties screen, select Device Settings tab. Click Disable, then click OK.