Hey. Download NullTCP from aminet. It's a text file with an example confg.
It's for TCP thought, so you'll need additional software to transfer files. A simple FTP program should work fine though.
This set up has the big advantage that it will allow you to share you PC internet connection with the Amiga (or vice versa I thinki). It's only 115kbps max thougt, so for transfering files it will be damn slow. The built in serial port of Amigas can only do 56kbps but there is software that substitutes the serial device that claims to achieve 115kbps. It's on aminet, so give it a try if you need a little more speed.
