you need to get the DDK from MS, you most likely need to
create a HID driver (human interface Device), the DDK is a
device driver Kit and you will need VC++ (visual C++) from
MS also. there are loads of examples on the CD for making
USB device drivers., the DDK was free the last time i looked
you will need to pay shipping and handling.
you Pic will need to responed to an ID request from the OS so that
windows can locate the driver it needs to use for your device..
if you go to the Intels Web site you can get the required USB
signitures that are expected so that this device can work 0n any
platform as long as the drivers are there.
the protocol for the coding it not that hard, its alittle different
than RS-232 but you will do fine.., it uses simpe CRC etc..