My experience has been that on must have manufacturer drivers installed to
disable the touchpad. I'm using a Dell D820, which uses the Alps touchpad
drivers. A clean install of Vista just uses the MS mouse drivers, which
allow me to use the pointing stick and the touchpad but offer no ability to
disable either.
I just downloaded the Alps XP drivers from Dell and installed them. got a
compatibility error after reboot but told Vista to run the program and was
able to disable the touchpad via the Alps utility program. If you're using a
Dell, take a look for program files\apoint and run apoint.exe. Otherwise,
you'll have to root around looking for your touchpad driver.
Lang