OSX reads most PC formats...
But either way.
Get a Cat5 cable (maybe straight, maybe crossover... it depends on how new your PC NIC or iBook are, and whether they support autosensing), plug them into each other (if your PC even has an NIC, that is), set up Windows file sharing on the ibook, set up both machines on the same subnet, give them IP addresses.
Via "Network Places" on the PC, let it connect to the iBook at:
\\IPADDRESS\user
Done.
If you need more detailed instructions, ask.
(NIC = network card, basically)