what version of MacOS? If it's OS X you have many ways to do this. You can connect them directly using cross-over ethernet cable or via a hub. In OS X, FTP is built in along with a Samba client. 10.2 has Samba server built in so Windows will see the machine as another Windows file sharing machine. Just enable "Windows file sharing" in the Services system preferences.
You could also buy
MacOpener and open the files on a Mac-formatted disk on the PC.
Maybe it's an older iMac running OS 8 or 9... in that case just format the floppy on the Mac as DOS. Then save files to the floppy. That would probably be the easiest way to transfer the files to be honest.