Lots of options.. Depends a bit on what you've got..
If it's an Amiga 500with workbench 1.3 it's a bit more dificult. If it's an Amiga 4000 with lots of extra's..
Cheepest; with good old floppy disks, needs Crossdos or something similar.
Serial cable; needs a cross serial cable (iirc), a bit more costly and can be troublesome to setup
Network; fast and good, can be expensive and hard to setup..
If you tell us the specs of the amiga and the PC I'm sure someone else can be more helpfull..
