Okay, first make sure it's a crossover and not a patch cable. You can tell by checking the colors of the wires inside the cable on each end. If they match perfectly, then you've got a patch cable, if they don't match, you've got the correct crossover cable.
Next, set each machine for DHCP (after you've plugged the cable into both). From there, each machine will give you an IP address. Try to ping one machine, from the other, either via its name or address. If that works, turn on filesharing and it should be set. If the ping doesn't work, then either your cable isn't the correct one, or you've got another problem all together.