Helping people with computers... one answer at a time.
I don't have a Sony so it might be a little different on your machine, but there are definitely places to look.
I'd start with the Mouse settings in Control Panel. I'd specifically look for something that allows you to control or turn off the touchpad. If that's not there, then in the Hardware tab therein, you could try disabling the device that corresponds to the touchpad. The only catch is that the device might not be called "Touchpad". As I sit here working on my Dell, the Touchpad is actually referred to as a PS/2 Port Mouse ... meaning that it's just mimicking a standard mouse.
Be prepared to know your keyboard-only interface if that disables your "other" mouse as well. That could happen, and the way to restore that is to re-enable the driver.
If, like my Dell, your computer has both a touchpad and an "eraser head" mouse, unless there's something specific for it in control panel, you'll be disabling or enabling both together.
If there's nothing in the Control Panel that allows you to control your touchpad, another place to look is in your system BIOS. When you boot your machine, before Windows begins loading, you're probably given the option to hit some key to enter setup, or press a function key to change BIOS settings. Exactly where will vary a great deal from one manufacturer to the next, but I have also seen options in the system BIOS that allow you to control it's behavior.