this is extremely easy if your XP machin has bluetooth or if you have a wireless router.
put all the OSX files into the "Public" folder. then use XP bluetooth to browse the files on the OSX.
or if the XP doesn't have bluetooth, but you have a wireless router the use the OSX to set up a computer to computer network and then use the XP to browse the public folder of the OSX.
if the XP machine doesn't have bluetooth and you dont have a wireless router, then its going to take more work.
i'll never buy another computer without bluetooth AND 802.11 protocol.