nileknight said:
In general if you follow these steps it will disable the PS/2 driver for the Touchpad on any laptop.

To disable the PS2 touchpad driver, you need to be the "Owner" of i8042prt.sys file under C:\Windows\System32\drivers.

-right click the file i8042prt.sys --> select Properties

- Select security, and edit security where your login has full control over the file.

- click apply

- go to device manager (right click windows-->device manager)

- expand mouse & other pointing devices

- right click PS/2 compatible mouse

- click on disable

Voila!
Good luck

With the last several updates from Microsoft Update, I have not had any issues in getting the settings remembered. It seems that if there is an update the setting to turn off the keypad when a mouse is plugged in may have to be redone. But, unless there is a new update, the setting stays put, at least for me.