This scanner is meant to operate as a bulk usb storage device, meaning that in 2k, XP, etc. you should be able to just plug it in and see a new drive of size 16Mb where your scans appear.
If it's not working, you may want to remove the driver in the Control Panel/Hardware section and plug it in again.
I'm looking for a Win98 driver for it right now, as Win98 doesn't support generic bulk USB, and requires a driver which HP's website is surprisingly reluctant to deliver.