Jumping cursor problem solved

I posted question about this last December and wasn't able to solve problem but finally discovered solution to it for myself so thought I would share it in case anyone else having the problem.  I was apparently brushing by touchpad when typing and must be super sensitive so I got a mouse.  I went into BIOS and 'turned off touchpad' I THOUGHT.  However cursor still jumped around so I decided to just live with it.  Then I was talking to a Dell Technician and discovered that the PS2 mouse will disable touchpad but the optical USB mouse did not.  I had a USB optical mouse so I thought AGAIN I'd have to just live with it but found that if I downloaded the new touchpad software on Dell.com site, it supports touchpad features for the optical mouse now, so optical USB mouse being connected will disable touchpad so my jumping cursor problem has finally stopped.  FYI !!