Are you talking about the new Aero preview features? Where when you hover over an icon it shows a preview? You can control that by modifying the registry. The location that holds this control is:
The "ExtendedUIHoverTime" DWORD is the time in milliseconds to wait when a mouse hover is detected to show the Aero preview (source).
The problem with input devices is that they all detect as a mouse pointer. Windows doesn't differentiate between a touchpad and a physical mouse. The only way I can think to change behavior when you plug in a mouse is to create a script that toggles the registry value. It's a clunky way to do it and I think it would be better to compromise on a time that fits in both situations.
Hope this helps