Disabling PS2 trackpad on I5000

I bought a used I5000 for my daughter's use around the house. The
standard USB port was damaged and unusable, but the rest of the computer
worked fine. I installed XP and she started using a USB mouse with a
PS/2 adapter. After a few weeks she got careless and the USB/PS2 adapter
tore out the PS/2 port in the back.

I scrounged up a USB2 cardbus card and now she has mouse support back,
however I can't turn off the trackpad and its buttons. I've gone into
the control panel and looked at the mouse drivers and there are two
listed: one is a PS/2 mouse and the other is her HID (Human Interface
Device) mouse. There is a way to disable the HID, but the option to
disable the PS/2 mouse is greyed out.

Does anyone have any clues on how to disable the trackpad?

Mike