SD-4 is Class Complaint and needs no drivers. There are no drivers written specifically for it and there should not need to be.

Please consult this recent thread from the BIAB forum where another user found out that a completely different USB device, a Logitech Quickcam, was preventing his system from reconizing his SD4's USB connect properly:

SD4 and USB problem solved

Don't know if that is your exact problem or not, but I did not have any problem with my SD4, just plugged it in to my XP SP3 computer and the USB was automatically recognized. I don't have a Quickcam.

--Mac