might try something like this (same idea as suggested by rjbull & jdd) - the cables shown in that TC link seem to be focused on copying stuff from older pc to newer one - in fact at least one of them seem to simply start copying stuff automatically according to an amazon review. They all work with their own software
FYI There is no 'special' software required with most of the USB datalink connections that are designed for this purpose, such as the one I mentioned earlier. You should be able to use any flavor of Windows Explorer software.
With XP, the drivers are loaded automatically when you connect the computers with the USB cables and, voila....you can copy or backup or move files from one to the other. Nothing should start copying or moving files automatically unless you set it up to intentionally do that.
You do not need to mess around with Internet connections or IP addresses, or work groups or pinging or any of this other stuff.