I once disabled my touchpad because I would rub against it while typing and it would move my mouse elsewhere. I have since re-enabled it from the same place (system -> preferences -> pointing device) but it remains disabled at next boot up.
I know it's a per-user setting, because when I logon as another user to the same laptop, touchpad remains enabled..
I disable touchpads on all my laptops because I cannot stand using them and stick to using a mouse.
I just started using a different laptop which is a Compaq CQ62-210US. It doesnt have a hot key option to do so so I did the obvious thing and turned off the software and deleted the driver. I have done everything I know how to do and the touchpad is still activated.
I have just upgraded to Ubuntu 11.04 (Gateway NV53u Laptop), with no problems except that I have lost the ability to scroll with my touchpad on my laptop.
Running xinput list shows that there is a PS/2 Mouse and AlpsPS/2 ALPS Glidepoint. Also, going through the Mouse and Pointer Device options, I see touchpad options, which I can fiddle with, but have no visible change.