Do you have problems typing on a laptop? Does the cursor seem to jump around making it a pain to type? Well, it is usually because your thumb probably brushes across the touchpad while typing and the cursor jumps to the location where the mouse pointer is on screen.
Most Operating Systems would provide an option to disable the touchpad tapping functionality while typing. This should solve the problem. To do this on Windows XP, go to Control Panel > Mouse > Advanced > Advanced Feature Settings > Tapping and Feature Settings > Tapping Settings and check the "Disable tapping during key input" check box. This setting may reside in different places in the Mouse control panel applet based on yor manufacturer/Touchpad driver. This was the sequence in my Toshiba laptop. [Found this from here, Q7 -- it actually gives a different sequence to reach this setting, which may be more generic]
If you use Linux, Ubuntu blog descrives a method to do this on Linux here.