No USB Port in "Scanner/Camera Installation Wizard

My OS is WIN2000 Professional on NT Technology. I've been
trying to install a Visioneer 7600 USB scanner. Using the
Start/Settings/Control Panel/Scanner and Camera-Add
function, I'm entered into the Scanner and Camera
Installation Wizard. I get to a screen that has Available
Ports and I'm suppose to select a USB port, but a USB port
is not showing as a selection.
I've downloaded the updated driver from Visioneer and all
I need to know is how to get 'USB Port' to show up in the
available ports in the Installation Wizard.
Since I can not enter the 'USB Port' text in the
Installation Wizard screen, I know there are other steps I
need to follow.
Any recommendations/suggestions.
Thank You.