I found a driver for my Dell Latitude D630 at ftp://ftp.dell.com/Pages/Drivers/latitude-d630.html, and even though it says it only works up to Windows Vista, it is working in Windows 7 after installing and rebooting. Just go to control panel to find your mouse settings and you will see the touchpad there.
I also have a Dell D630, and have a cursor that runs from one corner of the screen to the other all the time.
Hopefully will be able to figure out the problem soon. my theory is to disable all control devices on the computer, and install a new mouse (External).
AKA Computer Geek