I've had a discussion with Marc (IIP creator) about difficulty getting the newest IIP to copy uploads across a Windows peer<->peer network. It would stop and give an error message that there wasn't enough drive space on the HD on another computer.
Tested a work-around just now, and it worked fine ... simply use the "Map Network Drive" option from Window's "Explorer" file-managing system program to map the drive on the other machine to the uploading machine's list of "local" hard-drives, then from IIP, choose that "local" mapping of the other computer's hard-drive as a destination.
It's happy, we're happy, everything's fine here thank you ...

Neil